ACN 005 057 349 Pty Ltd v Commissioner of State Revenue [2015] VSCA 332

LIMITATION OF ACTIONS - Whether recovery of overpayments precluded by limitation periods - Postponement of limitation period - Whether mistake established - Whether mistake could have been discovered with reasonable diligence - Land Tax Act 1958 s 90AA - Limitation of Actions Act 1958 ss 5(1)(d) 20A and 27.

INTEREST - Whether compound interest recoverable - Exceptional circumstances - Conscious maladministration - Supreme Court Act 1986 ss 58 and 60.

Introduction and Summary ........................................................

The Commissioner's duplication error .........................................

The taxpayer's attempts to recover the excess payments ..................

The statutory framework ..........................................................

The judge's reasons ..................................................................

Issue 1 - Are the objection and refund regimes exclusive? .............

Issue 2 - Would a limitations provision bar the proceedings for restitution?.............................................................................................

Issue 3 - Can the power under s 19 be enforced by mandamus?........

Issue 4 - Would a limitations provision bar mandamus?....................

Issue 5 - Does compound interest apply?............................................

The appeals ...........................................................................

(1) What is the nature of the power to amend assessments under s 19? ....................................................................

(2) Did the Commissioner engage in conscious maladministration?................................................................

(3) What proposition does Royal Insurance stand for? .................

(4) What was the character of the alleged mistake?...................

(5) Would an underlying restitution claim be made out?..........

(6) Which limitation period applies - s 90AA, s 20A or s 5(1)?..................................................................

(7) Is the limitation period postponed under s 27?....................

(8) Is ACN entitled to compound interest? ...........................

Conclusion on the mandamus application/appeal ..........................

Conclusion on the restitution application/appeal ...........................

1 These two applications for leave to appeal[1] raise the following question: Where the Commissioner of State Revenue ('the Commissioner') has raised a land tax liability under the Land Tax Act 1958 ('the Act')[2] twice with respect to the same landholding, and the taxpayer has paid, can the excess payments be recovered by a proceeding for mandamus? In our view, in the circumstances of the case, the answer is 'yes'. We consider that the statutory power the Commissioner has to ensure assessments of land tax are complete and accurate under s 19 of the Act[3] gives rise to a duty in the circumstances of the case that can be enforced by mandamus to direct that excess payments be repaid. In our view, in the facts and circumstances present here, any relevant limitation period has been satisfied.

2 The applications are brought from a judgment and orders of a judge of the Trial Division who dismissed two proceedings brought by ACN 005 057 349 Pty Ltd ('ACN'), one for judicial review[4] of a determination of the Commissioner not to refund excess payments[5] it made as a result of assessments for the 1990-2002 land tax years, and one for restitution[6] at common law.[7]

3 For the reasons we set out below, we would grant leave to appeal, and allow the appeal, in both proceedings.[8]

(1) The starting point is that the discretionary power of the Commissioner, under s 19 of the Act, to amend an assessment, as he thinks necessary, to ensure its completeness and accuracy, is enlivened when he becomes aware that an assessment is incomplete or inaccurate.

(2) We consider that the evidence here was overwhelming that the duplication error[9] that the Commissioner expressly admitted making with respect to the 2008-2011 land tax years was also committed, relevantly, in the 1990-2002 land tax years.[10]

(3) Furthermore, we consider that the Commissioner knew that: (i) the duplication error occurred in each of the 1990-2002 land tax years; (ii) the assessments for the 1990-2002 land tax years were thereby inaccurate; and (iii) that he wrongly collected taxes that were not otherwise due. Indeed, we consider that he made an implied admission to that effect.

(4) In the circumstances the Commissioner's power under s 19 was enlivened.

(5) The sole question for determination is whether the Commissioner was bound to exercise the discretion he has to amend the assessments and whether, if he had a duty to do so, ACN is entitled to mandamus to compel him to do so.

(6) Finance Facilities Pty Ltd v Federal Commissioner of Taxation[11] holds that where a discretionary power can be exercised lawfully only in one way, mandamus can be ordered to compel the exercise of the discretion in the way in which it must be exercised; the 'may' becomes a 'must'.

(7) Given the nature of the power under s 19, and the circumstances of the case, the power could be exercised lawfully only in one way, namely, to amend the assessments for the 1990-2002 land tax years and to give effect to those amendments by making a refund; the Commissioner was under a duty to so act.

(8) The High Court in Federal Commissioner of Taxation v Futuris Corporation Ltd[12] recognised that an assessment is susceptible to judicial review where there has been conscious maladministration.

(9) The Commissioner has refused to perform his duty without good reason or justification; in the circumstances of the case he has acted with conscious maladministration.

(10) ACN is entitled to an order for mandamus compelling the Commissioner to perform his duty to exercise the power under s 19 to amend and to give effect to the amendments by making a refund.

(11) In Commissioner of State Revenue (Vic) v Royal Insurance Australia Ltd[13] the High Court held that the discretionary power conferred upon the Commissioner to make refunds in the event of overpayments gave rise to a duty to refund, enforceable by mandamus, where the Commissioner would be liable, under the general law of restitution, to repay payments made under a mistake.

(12) In the context of the power under s 19, we consider that it may not be necessary for there to be an antecedent and separate liability on the Commissioner to make restitution before the Commissioner can be compelled to enforce his duty; the question of whether there is such a requirement is open.

(13) However, if there is such a requirement, we consider that ACN's claim for restitution at common law would be made out. ACN made excess payments in response to the assessments for the 1990-2002 land tax years under a mistaken belief that it was legally obliged to make the payments on the basis that the assessments were accurate when, in truth, they were inaccurate.

(14) The availability of the s 19 power to provide a remedy does not circumvent the objection and refund regimes because, by contrast to those regimes, the s 19 power is enlivened only when the Commissioner knows that an assessment is incomplete and inaccurate. The power conferred by s 19 functions as a mechanism to ensure the integrity of the system of tax collection under the Act, namely, that the Commissioner collects the correct amount of tax.

(15) ACN could not with reasonable diligence have discovered its mistake before the Commissioner's express admission of the duplication error on 23 March 2012; any relevant limitation period is thereby postponed.

5 We begin by describing the duplication error committed by the Commissioner.

6 ACN was from 1988-2007 the registered proprietor of two adjacent properties which together carry the street address of 2 Ottawa Road, Toorak (Certificates of Title Volume 8055 Folio 686 and Volume 4567 Folio 364) ('the two properties').[14]

7 Relevantly, for each land tax year from 1990-2002, ACN paid amounts to the Commissioner in response to assessments of land tax made by the Commissioner under the Act with respect to the two properties that were described as follows:

(1) '2 Ottawa Road, Toorak, 3142' carrying the Land ID/Reference '995176/1 27424 L' until 2001 (inclusive), and '000995176/1 L27424' thereafter;[15] and

(2) '65 Albany Road, Toorak, 3142' carrying the Land ID/Reference '22429086/1 598039 T' until 2001 (inclusive), and '022429086' thereafter.[16]

8 The total amount paid by ACN to the Commissioner in respect of the two properties for the 1990-2002 land tax years was $603,452.

9 ACN also paid amounts to the Commissioner with respect to the two properties in response to assessments of land tax for the land tax years 20032007.

10 For the 2008-2011 land tax years, Streetriver Pty Ltd ('Streetriver') (a related company to ACN), the then registered proprietor of the two properties,[17] was assessed for land tax for '2 Ottawa Road' and '65 Albany Road'. On 23 March 2012, Martyn Pritchard ('Pritchard') of the Commissioner informed Mr Wayne Ngo ('Ngo'), a taxation adviser to Streetriver and ACN, by email ('the 23 March 2012 email') that in calculating the land tax liability for '2 Ottawa Road' for the 2008-2011 land tax years, an erroneous valuation had been applied that encompassed both of the two properties. This meant that the valuation for '2 Ottawa Road' had included both the landholding of '2 Ottawa Road' and the landholding of '65 Albany Road'. This was in addition to the separate valuation for '65 Albany Road'. The property described as '65 Albany Road' had thus been determined to be a 'duplicate property'. Pritchard promised to send amended assessments deleting '65 Albany Road' as a separate landholding and a refund.

Dear Mr Ngo

Streetriver Pty Ltd

2 Ottawa Road and 65 Albany Road, Toorak

I refer to the letter of 8 March 2012 from this Office advising that principal place of residence exemption cannot be granted in respect of the above lands.

Since that decision was made the State Revenue Office (SRO) has detected an error in the 2008, 2009, 2010 & 2010 [sic] assessments.

The lands owned by Streetriver are lot 1 Lodge Plan 27424 and lot 1 Title Plan 598039.

These lots appeared on the land tax assessment notices as 2 Ottawa Rd and 65 Albany Rd. Toorak respectively.

The property at 65 Albany Rd has been determined to be a duplicate property. This is because the valuation applied to 2 Ottawa Rd encompasses both lot 1 Lodge Plan 27424 and lot 1 Title Plan 598039. This has been confirmed by Peter Fitzgerald, Valuer/City of Stonnington.

Therefore the assessments have been amended by the deletion of 65 Albany Rd. Fully settled re-assessments for 2008 to 2011 will issue shortly.

As a result a refund is to be issued.

...

12 The Commissioner issued a cheque dated 12 April 2012 in favour of Streetriver for the amount of $300,238.75.

13 Ngo was aware that before 2007, ACN, which was then known as 65 Albany Road Pty Ltd, had owned the two properties.[18] Ngo raised with Kim Davis ('Davis'), a company director with both ACN and Streetriver, whether the duplication error referred to in the 23 March 2012 email may have extended to land tax assessments issued to ACN in earlier years. Until 23 March 2012 when the Commissioner notified Streetriver that he had committed the duplication error, ACN was unaware that the valuation used by the Commissioner for '2 Ottawa Road' had included the landholding of Lot 1 Title Plan 598039 as well as the landholding of Lot 1 Lodge Plan 27424.

14 On 27 March 2012, Ngo conducted a property search of the site reflecting the street address of '2 Ottawa Road' through the Victorian Department of Environment and Primary Industries. The property report showed the site as comprising two parcels of land with a combined total of 1,967 square metres. Lot 1 Lodge Plan 27424 (the landholding referred to as '2 Ottawa Road' in the 23 March 2012 email) has a total land area of 1,058 square metres and Lot 1 Title Plan 598039 (the landholding referred to as '65 Albany Road' in the 23 March 2012 email) has a total land area of 909 square metres.

15 Davis located the land tax assessments issued to ACN for the 2002-2007 land tax years but could not locate those for the years before the 2002 land tax year.

16 Ngo arranged for a request to be made of the Commissioner to obtain the land tax assessments for the 1983-2001 years. However, the Commissioner advised that the land tax assessment notices from 1983-2001 could no longer be retrieved from the State Revenue Office ('SRO') records.[19] However, assessment reports from the SRO ('the SRO assessment reports') could be located for each of those years. These are in the form of an Excel spreadsheet and contain all the relevant information used by the Commissioner in raising the land tax assessments for the 1983-2001 land tax years.

17 Ngo reviewed the land tax assessment notices for the 2002-2007 land tax years and the SRO assessment reports for the 1983-2001 land tax years. These revealed that the assessments for '2 Ottawa Road' for the 1990-2007 years included the land described in Lot 1 Lodge Plan 27424 as well as the land described in Lot 1 Title Plan 598039; that is, the landholding for '2 Ottawa Road' included the landholding for '65 Albany Road', representing a combined total of about 2,000 square metres of land. The land tax assessments before 1990 did not contain the duplication error.

18 On the basis of this review, Ngo prepared a table transcribing the 'site value' of the land described for the two properties, as referred to in the assessments or the SRO assessment reports used by the Commissioner, for the 1990-2007 land tax assessments. The site value of a taxpayer's landholdings provides the basis for the land tax assessments raised by the Commissioner. The aggregate taxable value of all land held by a taxpayer is multiplied by the applicable land tax rates to determine the taxpayer's land tax liability for the year. The table Ngo prepared is as follows:

Table 1****[20] _ - Site Values used by Commissioner_

19 It was not in dispute that the assessments generated by the Commissioner on the basis of these site values for the two properties were paid by ACN. Senior Counsel for ACN invited the Court, during the hearing of the appeals, to infer that the site values ascribed to '65 Albany Road' (Table 1) were internally generated within the SRO and were based on the site value of '2 Ottawa Road' which the Commissioner understood to refer to a landholding of 1,058 square metres (rather than based on an area of about 2,000 square metres) from which he calculated what the site value of '65 Albany Road' should be, given that it represented a landholding of 909 square metres. In other words, a site value was adopted for 65 Albany Road that was only a little less than the site value for '2 Ottawa Road'. The ratio between the site values thus reflected the ratio between the relative landholdings.[21]

20 The 23 March 2012 email referred to the City of Stonnington ('the Council'), and its Valuer, Peter Fitzgerald ('Fitzgerald'), as having confirmed to the Commissioner that the valuation that had been applied to '2 Ottawa Road' encompassed both Lot 1 Lodge Plan 27424 and Lot 1 Title Plan 598039. Ngo arranged for Fitzgerald to be contacted by an employee of his firm, Daniel Mitchell ('Mitchell'), to determine the valuation history. On 2 May 2012 Fitzgerald provided Mitchell, by email, with a list of the dates when a new valuation was determined by the Council for '2 Ottawa Road' between 1992-2007 and the amount of each new site value:

21 On the basis of that history, Ngo prepared a table showing the date when a new valuation was determined for '2 Ottawa Road' and the new site value of the property between 1992-2006.

22 The new site values provided by Fitzgerald broadly correspond to the site values used by the Commissioner in the land tax assessments issued to ACN. For example, it is apparent from Table 2 (and recorded in Table 3) that on 1 October 1996 the new site value for '2 Ottawa Road' was $1,300,000. ACN's land tax assessment for 1998, based on land owned at midnight at 31 December 1997,[22] shows the site value of '2 Ottawa Road' as having increased to $1,300,000 (as recorded in Table 1). Similarly, on 1 July 2002 the new site value for '2 Ottawa Road' increased to $2,941,000 (as is apparent from Table 2 and recorded in Table 3) and ACN's land tax assessment for 2004, based on land owned at 31 December 2003, shows the new site value for '2 Ottawa Road' as having increased to $2,941,000 (as recorded in Table 1).

23 In response to Fitzgerald furnishing the valuation history in Table 2, Mitchell sent him a follow-up email on 3 May 2012 seeking confirmation of the land area used in respect of each of the valuations, and, in particular, whether the land area used for each of the valuations of '2 Ottawa Road' was approximately 2,000 square metres.

24 As indicated above,[23] a landholding of approximately 2,000 square metres would reflect the total combined area of Lot 1 Lodge Plan 27424 (1,058 square metres) and Lot 1 on Title Plan 598039 (909 square metres).

Thanks Peter.

Are you able to confirm the land area in relation to each of the valuations below [Table 2], or alternatively simply confirm that each of the valuations below was based on a property size of approximately 2,000 sqm?

Thanks again for your help.

Regards,

Daniel.

26 Fitzgerald confirmed by email on 3 May 2012 that a landholding of approximately 2,000 square metres had been used for the valuation of '2 Ottawa Road' for all the valuations he had provided. He said:

Can confirm that the same land area (2,000 approx.) was used in relation to all.

R'gds

Peter Fitzgerald

City Valuer

City of Stonnington

27 Viewing the email chain as a whole, Fitzgerald's confirmation was to the effect that each of the new site valuations determined for '2 Ottawa Road' between 1992-2007 (as recorded in Table 2) had been based on a landholding of approximately 2,000 square metres.

28 In our view, as the actual landholding of Lot 1 Lodge Plan 27424 is only 1,058 square metres, the uncontested evidence of Ngo demonstrates that the new site valuations determined by the Council for '2 Ottawa Road' between 1992-2007 (as recorded in Table 2) were based upon the combined total landholding of Lot 1 Lodge Plan 27424 (1,058 square metres) together with the landholding in Lot 1 Title Plan 598039 (909 square metres). This is important for our disposition of the appeals. More significantly, as many of the site valuations used by the Commissioner between 1990-2007 (as recorded in Table 1) broadly correspond to the valuations used by the Council, and particularly the new site values determined by the Council (as recorded in Table 2), in our view it should be inferred from the evidence that '65 Albany Road' was a duplicate property throughout 1990-2007, especially as the land tax assessments between 1992-2007 for '2 Ottawa Road' were based upon the valuations used by the Council for that period. Indeed, in the judge's reasons, she described it as 'common ground that the valuation used for land tax purposes in each relevant year from 1993 was essentially the same as that which was used by the City of Stonnington for municipal purposes'.[24]

29 It follows that the assessments between 1990-2007 were based on an assumption that the landholding for '2 Ottawa Road' was approximately 2,000 square metres. For each of those years it was a mistake for the Commissioner to issue a separate assessment for '65 Albany Road' because its landholding of 909 square metres (Lot 1 Title Plan 598039) had already been included within the 2,000 square metreage attributed to '2 Ottawa Road'. We infer that without the mistaken inclusion of the landholding of 909 square metres (representing Lot 1 Title Plan 598039) the land tax assessment for '2 Ottawa Road' would have reflected a landholding of only 1,058 square metres (representing Lot 1 Lodge Plan 27424) and given rise to a proportionately smaller liability for land tax. The error made by the Commissioner was thus to raise an assessment for '2 Ottawa Road' that applied a valuation reflecting both the landholding of Lot 1 Title Plan 598039 in addition to the landholding of Lot 1 Lodge Plan 27424, as well as raising a separate assessment for land tax for '65 Albany Road' that applied a valuation for the landholding of Lot 1 Title Plan 598039. The Commissioner precisely identified the error when he conceded in the 23 March 2012 email that '65 Albany Road' (Lot 1 Title Plan 598039) had been determined to be a 'duplicate property'. In other words, the Commissioner had erroneously raised a land tax liability twice with respect to the same landholding.

30 The uncontested evidence of Ngo, including his evidence of the site values used by the Commissioner for the land tax years 1990-2007 and his evidence of the valuations used by the Council for the years 1992-2007, supports the proposition, which we accept, that the Commissioner erroneously raised a land tax liability twice with respect to the same landholding for each of the land tax years 1990-2007, and not only for the land tax years 2008-2011 which he conceded. We consider that this inference especially follows from a comparison between the valuations used for '2 Ottawa Road' by the Commissioner as recorded in the assessments or the SRO assessment reports (Table 1) and the valuations provided by the Council (Table 2 (New SV)) together with the evidence that the Council valuations for '2 Ottawa Road' were based upon a landholding of approximately 2,000 square metres, the metreage of the two properties. As mentioned, we consider that the congruence of valuations between those used by the Commissioner and many of those used by the Council indicates that the Commissioner relied on the Council's valuations for '2 Ottawa Road' between 1990-2007.[25] It follows that, in doing so, he treated '2 Ottawa Road' as being a landholding of approximately 2,000 square metres (that is, as incorporating the landholding of '65 Albany Road') while yet raising a separate assessment for '65 Albany Road'. He inaccurately listed the landholdings held by ACN. We consider that, considering the overall circumstances, the evidence here was overwhelming that the duplication error that the Commissioner expressly admitted making with respect to the 2008-2011 land tax years was also committed in the 1990-2002 land tax years.

31 More particularly, we find that the Commissioner erroneously raised a land tax liability twice for Lot 1 Title Plan 598039 ('65 Albany Road') for each land tax year between 1990-2007, relevantly, the 1990-2002 land tax years, which ACN paid, and not only for the land tax years 2008-2011 which the Commissioner conceded. We consider that we are as well placed as the judge below to arrive at a factual finding as there was no oral evidence given at trial, the evidence being given by affidavit alone and there being no cross-examination.[26]

32 On these matters we differ from the approach adopted by the judge. With great respect to her Honour, we consider that she was wrong not to make a finding that the duplication error that had occurred in the 2008-2011 land tax years had also occurred throughout, relevantly, the 1990-2002 land tax years.[27] We examine the judge's reasons in detail below.

33 As we explain further below, we also consider that the Commissioner was correct to recognise, as he did in the 23 March 2012 email with respect to the land tax years 2008-2011, that a correction of the duplication error required that the assessments be 'amended by the deletion of 65 Albany Rd'[28] and excess payments be repaid. While the Commissioner initially confined his approach to the land tax years 2008-2011,[29] we consider that this approach was correct and should have been applied to all the land tax years in respect of which the duplication error was made. Relevantly, we consider that the Commissioner's approach to the correction of the duplication error by means of the issuing of an amended assessment should have been applied to the land tax years 1990-2002 and not only to the land tax years of 2008-2011.

The taxpayer's attempts to recover the excess payments

34 Ngo prepared a further table summarising the amount of ACN's original land tax assessments for the 1990-2007 years, the estimated correct land tax assessment, and the estimated amount of land tax that had been overpaid as a result of the duplication error. This was based on the land tax assessment notices for 2002-2007 and the SRO assessment reports for the 1990-2001 land tax years:

Table 4 - Estimated Overpaid Land Tax 1990-2007

35 On 18 May 2012 Ngo made a formal request to the Commissioner requesting a refund of the 2007 overpaid land tax.[30] On 22 May 2012 he lodged with the Commissioner two Notices of Objection, the first against the 2006 and 2007 land tax assessments and the second against the 1990-2005 land tax assessments, claiming that an excessive amount of land tax had been assessed and paid in these years by reason of the duplication error. The Commissioner allowed the objection against the 2006 and 2007 land tax years[31] and issued a refund of $110,635 with respect to the 2006 assessment and $103,800 with respect to the 2007 assessment. These amounts correspond to the calculation of overpayments in Table 4 for those years, respectively. The refunds were made initially without interest. The Commissioner later accepted that interest would be allowed. With respect to the 1990-2005 land tax years the Commissioner's position was that he did not have the discretion to accept the out of time objection with respect to those years.

36 The Commissioner issued amended assessments for the 2006 and 2007 land tax years removing the landholding at Lot 1 Title Plan 598039 ('65 Albany Road') from those assessments. He did this by first removing both '65 Albany Road' (then with the Land ID 995176) and '2 Ottawa Road' (then with the Land ID 22429086)[32] and replacing both those landholdings with a single '2 Ottawa Road' and giving it a new Land ID 039663162:

Dear Sir/Madam

Amendment to Statement of Lands

Properties removed since the last assessment was issued

37 The amended assessment for the 2006 land tax year was relevantly in the following terms:

Re-Assessment - 2006 Land Tax Notice

65 Albany Road Pty Ltd

Issue date: 01 Feb 2013

PAY IN FULL

Total tax payable: $0.00

...

2006 Calculation of Land Tax Payable

...

Statement of lands owned as at midnight 31 December 2005 ...

38 We note that the taxable value of the landholding was $3,591,000 and this reflects the site value used by the Council for '2 Ottawa Road' (reflecting the landholding of approximately 2,000 square metres) from 1 July 2004 (as recorded in Tables 2 and 3). We also note that the tax was $67,515.00 which Table 4 records as the estimated land tax assessment for 2006 excluding the duplicated '65 Albany Rd'. That sum having been paid, the amended assessment was nil and, as mentioned,[33] the overpayment of $110,635 (as also reflected in Table 4) was refunded.

39 The amended assessment for the 2007 land tax year was relevantly as follows:

Re-Assessment - 2007 Land Tax Notice

65 Albany Road Pty Ltd

Issue date: 01 Feb 2013

PAY IN FULL

Total tax payable: $0.00

...

Notional 2007 Calculation of Land Tax Payable

Statement of lands owned as at midnight 31 December 2006 ...

40 We note that the taxable value was $4,630,000 and this reflects the site value used by the Council for '2 Ottawa Road' from 1 July 2006 (as recorded in Tables 2 and 3). We also note that the tax was $87,500.00 which Table 4 records as the estimated land tax assessment for 2007 excluding the duplicated '65 Albany Road'. That sum having been paid, the amended assessment was nil and, as mentioned,[34] the overpayment of $103,800 was refunded.[35]

41 By letter dated 3 December 2012 Ngo further requested of the Commissioner that he issue amended assessments for the 1990-2005 land tax years by exercising his discretion under s 19 of the Act.[36] This was not done but the Commissioner suggested that an application be made to the Treasurer for ex gratia relief.

42 Ngo wrote to the then Treasurer of the State of Victoria, the Honourable Kim Wells, requesting ex gratia relief for the overpayments made for the 1990-2005 land tax years. He wrote separately to the Treasurer requesting that he, on behalf of the Governor in Council: (1) extend time for ACN to object against the assessments; and (2) extend time for ACN to apply for a refund of tax.

43 The Treasurer responded by granting ex gratia relief for the 2003, 2004 and 2005 land tax years in the sums of $107,970, $129,250 and $114,774 respectively. The refunds correspond exactly to the calculation of the overpayments in Table 4. No interest was paid on the ex gratia payments. No ex gratia refund was granted for the land tax years before 2003.

44 Ngo prepared a table of estimated overpayments made by ACN confined to the years 1990-2002,[37] as these remain the only claims in issue. The total claimed is $363,680 ('the excess amount'):

Table 5 - Estimated Overpaid Land Tax 1990-2002

45 On 21 March 2013 ACN brought a proceeding in the Supreme Court against the Commissioner seeking relief in the nature of mandamus and a proceeding seeking restitutionary relief. The application for mandamus sought to enforce a duty to amend the assessments for the 1990-2002 land tax years and to refund the excess amount. The application for restitutionary relief was based upon a claim that the Commissioner, by its notices of assessment for the 1990-2002 land tax years, had demanded payment of amounts of land tax that were not authorised or payable under the Act, namely the excess amount. ACN had paid the excess amount in the mistaken belief that the land tax liability as assessed by the Commissioner was properly due and payable under the Act, and that ACN was legally obliged to make those payments.

46 The evidence of Davis further elaborated upon the nature of the mistake under which ACN alleged it paid the excess amount. He said:

The plaintiff [ACN] paid the land tax assessments for the 1990 to 2002 land tax years inclusive in good faith and in the belief that each land tax assessment issued by the defendant [the Commissioner] constituted a proper and lawful demand for the payment of all the tax assessed.

47 He emphasised that, in paying the excess amount, ACN held the mistaken belief that the landholdings recorded in the assessments for the 1990-2002 land tax years were accurate. Davis said:

The plaintiff [ACN] paid these land tax assessments in the belief that it was legally obliged to make these payments, and in the mistaken belief that the landholdings listed for the plaintiff in the assessments issued by the defendant [the Commissioner] for these years were accurate.[38]

48 We have already concluded that the landholdings listed for ACN in the assessments issued by the Commissioner for the 1990-2002 land tax years were inaccurate and that during those years the Commissioner erroneously issued a land tax liability twice for Lot 1 Title Plan 598039 ('65 Albany Road') for each of those years.[39] ACN's belief in the accuracy of the landholdings listed by the Commissioner was thus indeed mistaken. We consider that in describing the nature of ACN's belief when paying the excess amount it is necessary to take into account not only the belief that ACN was legally obliged to make the payment but also that ACN believed that the demand made by the Commissioner was based upon an accurate record of the landholdings ACN owned. In our description of ACN's belief we differ from the judge. This issue assumes some importance in our reasoning below.[40]

49 By letter dated 15 August 2013 the Commissioner advised Ngo that he had decided to exercise the discretion to issue amended assessments under s 19 and would do so by not making any amendment. The reason he gave for the refusal to amend was because a limitation period under the Act would preclude ACN successfully recovering the excess amount; that is, he refused to amend because he considered that ACN would not be entitled to any consequential relief, regardless of the merits.[41] He said:

After careful consideration of all the issues involved, I advise that the Commissioner has decided to exercise the discretion conferred on him by section 19 of the Act. The decision of the Commissioner is not to make any amendment to the assessments.

The discretion conferred by section 19 must be exercised having regard to [the] subject matter, scope and purpose of the Act as a whole. The primary reason for the Commissioner's decision is that, whether or not each of the assessments were now amended as requested, and even putting to one side the fact that no objection was lodged in accordance with section 24A, your client would not be entitled to the consequential relief sought; that is, pursuant to section 90AA of the Act, your client would still not be entitled to the refund it seeks.[42]

50 In the light of this response ACN amended its originating motion in the mandamus proceeding alleging that the Commissioner acted on the basis of a legally erroneous view that amended assessments that eliminated the duplication error could not result in any repayment to ACN. This was developed below into the allegation of conscious maladministration.[43] It is a serious and important allegation in the circumstances of the case.

51 The mandamus case is based upon the Commissioner's constructive refusal to exercise his power to amend the assessments for the 1990-2002 land tax years in response to the request by ACN by letter dated 3 December 2012[44] and the Commissioner's actual refusal to exercise his power to amend the assessments by his letter dated 15 August 2013.[45]

52 The Act confers a power on the Commissioner to charge, levy and collect land tax, in the case of each owner of land, for every dollar of the unimproved value of the land, pursuant to s 6. Section 8 provides that tax shall be assessed, charged, levied and collected on the total unimproved value of the land at midnight on the 31st of December immediately preceding the year for which the tax is assessed. This is reflected in the extracts of the 2006 and 2007 assessments referred to above.[46] There are numerous exemptions provided for under s 9 (for example, land used by a charitable institution exclusively for charitable purposes[47] and land outside the metropolitan area used for primary production[48]) as well as a 'principal place of residence' exemption under s 13A.

53 Section 14 requires taxpayers to furnish returns containing statements of the land owned:

14. Taxpayers to furnish returns

For the purposes of the assessment and levy of taxation every taxpayer shall as hereinafter provided furnish to the Commissioner returns setting forth a full and complete statement of his land with such other particulars as are prescribed.

54 However, the Commissioner has the power to issue an assessment in the absence of a return from the taxpayer.[49] There was no evidence before the judge that ACN had furnished returns or of any practice adopted by the Commissioner that ACN's land tax assessments between 1990-2002 were based upon returns.

55 Section 15(1) renders every taxpayer 'liable for the making of returns of land and for the payment of the whole amount of tax (if any) assessed thereon respectively'.

56 Section 16 permits the Commissioner to use valuations from a rating authority or the Valuer-General for the purpose of an assessment:

16. As to use of valuations by Commissioner

For the purpose of the assessment and levy of taxation the Commissioner may use -

(a) valuations made by a rating authority within the meaning of the Valuation of Land Act 1960;

(b) valuations made by the Valuer-General or a valuer nominated by the Valuer-General.

57 A 'rating authority' under the Valuation of Land Act 1960 includes 'any council in respect of its powers under any Act'.[50] 'Council' has the same meaning as in the Local Government Act 1989,[51] namely, relevantly, 'a municipal council'.[52]

58 Section 17 permits the Commissioner to use, as the basis of his assessments, returns furnished by a taxpayer, or other information in his possession, or any one of those sources:

17. Assessments to be made by Commissioner

The Commissioner shall from the returns and from any other information in his possession or from one of those sources and whether any return has been furnished or not cause an assessment to be made of the taxable value of the land owned by any taxpayer and of the land tax payable thereon.

59 Section 18 provides for default assessments to be made by the Commissioner in the absence of returns:

18. Default assessments

If -

(a) a taxpayer makes default in furnishing a return;

(b) the Commissioner is not satisfied with the return made by any taxpayer; or

(c) the Commissioner has reason to believe that any person (though he may not have furnished a return) is a taxpayer -

the Commissioner may make an assessment of the amount which, in his judgment, is the taxable value of the land owned by the taxpayer and of the land tax payable thereon, and the land tax so assessed shall be the land tax payable by that taxpayer unless the assessment is varied in accordance with the provisions of this Act.

60 Section 19 confers a discretion on the Commissioner to amend assessments for the purposes of ensuring completeness and accuracy. This is the power that ACN seeks to enforce by mandamus:

19. Amended assessments

The Commissioner may from time to time amend an assessment by making such alterations or additions to it as he thinks necessary to ensure its completeness and accuracy, and shall notify to the taxpayer affected every alteration or addition which has the effect of imposing any fresh liability or increasing any existing liability and unless made with the consent of the taxpayer every such alteration or addition shall be subject to objection in the same manner and to the same extent as the original assessment but the validity of an assessment shall not be affected by reason only that any of the provisions of this Act have not been complied with.

61 Section 20 is a 'conclusive evidence' provision that entitles the Commissioner to rely on assessments as conclusive evidence of the assessment's accuracy. Section 20 could not be relied upon here with respect to the 1990-2002 land tax years as the Commissioner was unable to produce assessments for those years. It provides:

20. Evidentiary provisions

(1) The production of an assessment or of a document under the hand of the Commissioner purporting to be a copy of an assessment shall -

(a) be conclusive evidence of the due making of the assessment; and

(b) be conclusive evidence that the amount and all the particulars of the assessment are correct, except in proceedings on review or appeal against the assessment, when it shall be prima facie evidence only.

(2) The production of any document under the hand of the Commissioner purporting to be an extract from any return or assessment shall in relation to any matter other than a matter referred to in sub-section (1) be prima facie evidence of the matter therein set forth.

62 A person dissatisfied with an assessment has a right to make an objection under s 24A within 60 days after service of the notice of assessment:

(1) Any person who is dissatisfied with the assessment of the Commissioner relating to a duty of land tax charged, levied and collected under this Act other than Part IIB,[[53]] may give to the Commissioner within 60 days after service of the notice of the assessment an objection in writing against the assessment stating fully and in detail the grounds on which he relies but the Commissioner must not entertain any objection relating to the unimproved value of land where the assessment is based on a valuation made under the Valuation of Land Act 1960.

(2) The Commissioner shall consider every written objection made by a taxpayer and may make such inquiries thereon or relating thereto as he thinks fit.

(3) If the Commissioner considers that any objection should be allowed either wholly or in part he may alter or amend the assessment accordingly.

(4) The Commissioner shall give the taxpayer written notice of his decision on the objection.

63 Section 25 permits taxpayers who are dissatisfied with the decision of the Commissioner on an objection to request the Commissioner (within 60 days) to refer the decision to the Victorian Civil and Administrative Tribunal ('the Tribunal') for review or to treat the objection as an appeal to be heard in the Trial Division of the Supreme Court:

25. Reviews

(1) If the taxpayer is dissatisfied with the decision of the Commissioner on the objection he may within 60 days after notice of the Commissioner's decision has been given to him ...

(a) in writing request the Commissioner to refer the decision to the Victorian Civil and Administrative Tribunal for review; or

(b) in writing request the Commissioner to treat his objection as an appeal and to cause it to be set down for hearing at the next sittings of the Supreme Court.

...

64 Section 26 imposes on the taxpayer the burden of proving that the assessment is excessive and limits the taxpayer to the grounds stated in the objection unless the Court or Tribunal allows otherwise:

26. Proceedings on references and appeals

(1) Upon any review or appeal under this Act -

(a) unless the Court or the Tribunal otherwise orders, the taxpayer shall be limited to the grounds stated in his objection and the Commissioner shall be limited to the grounds upon which he has disallowed the objection; and

(b) the burden of proving that the assessment is excessive shall lie upon the taxpayer.

(2) If the assessment has been reduced by the Commissioner after considering the objection, the reduced assessment shall be the assessment to be dealt with on the review or appeal.

65 Section 38(1) provides that a pending objection or appeal or case stated does not affect the assessment and 'tax may be made, levied and recovered on the assessment in like manner as if no objection had been received and no appeal or case stated were pending'.

66 Section 39 provides for sums payable for tax to be debts due to the Crown:

39. Land tax a debt due to Her Majesty

Every sum payable for tax shall when the same falls due be deemed a debt due to Her Majesty by the owner of any land who shall forthwith pay the same to the Commissioner.

67 ACN emphasises that s 39 does not refer to assessments as giving rise to a statutory debt; rather, there must be a 'sum payable for tax' before the debt is generated.[54]

68 Section 57 provides that land tax is due and payable on the date stipulated in the assessment:

57. Dates for payment of tax to be stated in notice of assessment

Subject to this Act, land tax for each year shall be due and payable on a date stated in the notice of assessment to be the due date which date shall not be less than fourteen days after the service of such notice.

69 Section 59 provides for the Commissioner to recover tax (and any additional tax arising from an amended assessment) on behalf of the Crown by issuing proceedings in his own name in the County Court or the Magistrates' Court.

70 Section 67 stipulates that no statute of limitations 'shall bar or affect any action or remedy for recovery of tax'.

71 If a person claims to be entitled to a refund of tax he or she has three years from the date of payment to lodge with the Commission an application for a refund. The Commissioner relies upon s 90AA to preclude any recovery for ACN in the mandamus proceeding or the proceeding for restitution, more than three years having elapsed since any of the payments were made with respect to the 1990-2002 land tax years and no relevant application under s 90AA having been made to the Commissioner:

90AA. Refund of tax

(1) Proceedings for the refund or recovery of tax paid under, or purportedly paid under, this Act, whether before or after the commencement of section 22 of the State Taxation (Further Amendment) Act 1993, must not be brought, whether against the Commissioner or otherwise, except as provided in this section.

(2) If a person claims to be entitled to receive a refund of or to recover tax paid under, or purportedly paid under, this Act, the person must lodge with the Commissioner within 3 years after the payment was made an application in the prescribed form for the refund of the payment.

(3) If -

(a) a person has lodged an application for the refund of an amount in accordance with sub-section (2); and

(b) the Commissioner has not, within the period of 3 months after the application was lodged -

(i) refunded the amount; or

(ii) applied the amount in accordance with sub-section (6)(d); or

(iii) refunded part of the amount and applied the remainder in accordance with sub-section (6)(d) -

or has, in writing given to the person within that period, refused to make a refund, the person may, within 3 months after the end of that period or after that refusal, whichever first occurs, bring proceedings for the recovery of the amount, or, if the Commissioner has refunded or applied part, the remainder of the amount.

(4) Sub-section (3) applies whether or not the period for bringing proceedings for the refund or recovery of the amount prescribed by section 20A(1) of the Limitation of Actions Act 1958 has expired.

(5) Sub-sections (1) and (2) do not apply to a person if the person claims to be entitled to receive a refund or to recover tax paid under, or purportedly paid under, this Act by reason of the invalidity of a provision of this Act.

(6) If -

(a) an application for a refund is lodged with the Commissioner in accordance with sub-section (2); and

(b) the Commissioner finds that an amount has been overpaid by the applicant -

the Commissioner -

(c) must refund the overpaid amount; or

(d) must -

(i) apply the overpaid amount against any liability of the applicant to the State, being a liability arising under, or by reason of, an Act of which the Commissioner has the general administration; and

(ii) refund any part of the overpayment that is not so applied.

(7) If, under this section, the Commissioner determines to refund an amount, the amount is payable from the Consolidated Fund which is to the necessary extent appropriated accordingly.

(8) In this section, 'proceedings' includes -

(a) seeking the grant of any relief or remedy in the nature of certiorari, prohibition, mandamus or quo warranto, or the grant of a declaration of right or an injunction; or

(b) seeking any order under the Administrative Law Act 1978.

72 The Commissioner also emphasises the express power of appropriation found in s 90AA(7) which is absent from s 19.

73 The limitation period of three years for an application to be made under s 90AA was relied upon by the Commissioner in his letter of 15 August 2013 to Ngo referred to above[55] as disentitling ACN to any refund regardless of the merits of otherwise exercising the power under s 19 to amend the assessments for the 19902002 land tax years.

74 Section 92A of the Act makes it clear that s 90AA is intended to restrict the jurisdiction of the Supreme Court to order relief:

92A. Supreme Court - limitation of jurisdiction

It is the intention of this section to alter or vary section 85 of the Constitution Act 1975 to the extent necessary to prevent the Supreme Court entertaining proceedings of a kind to which section 90AA(1) applies, except as provided in that section.

75 There are other potentially relevant limitation periods prescribed under the Limitation of Actions Act 1958 ('the Limitations Act'). These include the period of six years from the date on which a cause of action accrued founded on simple contract, including contracts implied by law (s 5(1)(a)), and in respect of a proceeding to recover any sum recoverable by virtue of an enactment (s 5(1)(d)):[56]

5 Contracts and torts

(1) The following actions shall not be brought after the expiration of six years from the date on which the cause of action accrued -

(a) Subject to subsections (1AAA), (1AA) and (1A), actions founded on simple contract (including contract implied in law) or actions founded on tort including actions for damages for breach of a statutory duty;

(b) Actions to enforce a recognizance;

(c) Actions to enforce an award, where the submission is not by an instrument under seal;

(d) Actions to recover any sum recoverable by virtue of enactment, other than a penalty or forfeiture or sum by way of penalty or forfeiture.

76 Section 20A of the Limitations Act specifically addresses proceedings for the recovery of money paid by way of tax, or purported tax, or attributable to tax or purported tax, paid under a mistake of law or of fact:

20A Limitation on proceeding for recovery of tax

(1) Subject to subsection (2), a proceeding for the recovery of money paid by way of tax or purported tax or by way of an amount that is attributable to tax or purported tax under a mistake (either of law or of fact) or under colour of authority must be commenced -

(a) within 12 months after the date of payment; or

(b) in the case of a proceeding in accordance with another Act that provides for the refund or recovery of the money within a longer period, within that longer period.

(2) Despite anything to the contrary in any other Act, if money paid by way of tax or purported tax or by way of an amount that is attributable to tax or purported tax is recoverable because of the invalidity of a law or provision of a law, a proceeding for the recovery of that money must (whether the payment was made voluntarily or under compulsion) be commenced within 12 months after the date of payment.

77 Section 27 allows for the postponement of an otherwise applicable limitation period, relevantly, where the proceeding is for relief from the consequences of a mistake, from the date when the taxpayer discovered the mistake or could with reasonable diligence have discovered it:

27 Postponement of limitation periods in case of fraud or mistake

Where, in the case of any action for which a period of limitation is prescribed by this Act -

(a) the action is based upon the fraud of the defendant or his agent or of any person through whom he claims or his agent; or

(b) the right of action is concealed by the fraud of any such person as aforesaid; or

(c) the action is for relief from the consequences of a mistake -

the period of limitation shall not begin to run until the plaintiff has discovered the fraud or the mistake, as the case may be, or could with reasonable diligence have discovered it:

Provided that nothing in this section shall enable any action to be brought to recover or enforce any charge against or set aside any transaction affecting any property which -

(i) in the case of fraud, has been purchased for valuable consideration by a person who was not a party to the fraud and did not at the time of the purchase know or have reason to believe that any fraud had been committed; or

(ii) in the case of mistake, has been purchased for valuable consideration, subsequently to the transaction in which the mistake was made by a person who did not know or have reason to believe that the mistake had been made.

78 To foreshadow the submissions made on the appeals, the Commissioner's primary position is that both the mandamus proceeding and the restitution proceeding are precluded by s 90AA of the Act and that the Limitations Act provisions (ss 5(1), 20A) do not apply. However, if either s 5(1) or s 20A do apply, the Commissioner claims that the time periods they prescribe have been exhausted and ACN cannot take the benefit of postponement under s 27 as it could with reasonable diligence have discovered the duplication error for the 1990-2002 land tax years many years ago.

79 By contrast ACN's primary position is that no limitation period governs the exercise of the power of the Commissioner under s 19 to amend assessments. The power may be exercised 'from time to time', that is, at any time. If any limitation period does apply it is s 20A(1), which is the more specific, and later enacted,[57] provision addressing the circumstances here, rather than s 90AA of the Act. If not s 20A(1), then s 5(1)(d) would apply. ACN submits that it can take the benefit of the postponement period under s 27 as it could not with reasonable diligence have discovered the duplication error for the 1990-2002 land tax years until alerted by the 23 March 2012 email that the Commissioner's duplication error had occurred for the 2008-2011 land tax years.

80 The judge identified five principal issues as arising for determination,[58] namely:

(1) Where a taxpayer contends it has 'overpaid' land tax assessed under the Act, is it open for the taxpayer not to avail itself of the objection process and instead sue at common law to recover the alleged 'overpayment' amount as money had and received?

(2) Is ACN's action in restitution for relief from the consequences of a mistake barred by a limitation provision - be it one or more of s 90AA of the Act, s 20A or s 5(1) of the Limitations Act, as extended by s 27 as the case may be?

(3) Is an order for mandamus (or other order on judicial review) available to direct the Commissioner to exercise the discretion conferred by s 19 of the Act and issue amended assessments to ACN for each of the 1990-2002 land tax years?

(4) Is ACN's action for mandamus (or other order on judicial review) barred by any limitation provision?

(5) If ACN establishes that it is entitled to a refund of, or to recover, the alleged excess amount, is compound interest recoverable as part of the restitutionary relief or is ACN limited to recovering simple interest, in the Court's equitable jurisdiction or alternatively pursuant to ss 58 or 60 of the Supreme Court Act 1986?

Issue 1 - Are the objection and refund regimes exclusive?

81 With respect to Issue 1, the judge concluded that the statutory scheme under the Act provided for an exclusive and exhaustive regime for the recovery of tax, or purported tax, under the Act, namely the objection regime[59] and the refund regime.[60] That being so, there was no scope for a taxpayer to commence a proceeding at common law to recover alleged overpayments on a claim for restitution. After a careful consideration of the statutory provisions in the Act governing the making of objections, and the processes of reviews and appeals from decisions with respect to those objections, the judge concluded that the objection regime, together with the process for claiming a refund under s 90AA, functioned to exclude any other mechanism for recovery.

In the present case, if the plaintiff were permitted to pursue its restitutionary claim at common law, it would circumvent the statutory regime and the time frames and processes limited for challenging the land tax so assessed. In my view, the statutory regime of objections and appeals established under the LTA 1958,[[61]] together with the process for claiming a refund under s 90AA, provides the only means for a taxpayer to establish that there is an overpayment, and thereby any entitlement or remedy for the recovery of any overpaid tax. In other words, the position is that unless and until the original assessment is set aside or varied or shown to have been excessive, and the amount of tax so assessed never to have been exigible, no common law claim for restitutionary relief could be pursued. Indeed, when the provisions of s 90AA are examined (as to which, see Issue 2 below), it appears that the legislature intended that, save in the case where invalidity of a provision is alleged, there would only be scope for a person who claims to be entitled to receive a refund of or to recover tax paid under the LTA 1958 to bring proceedings for the recovery of the amount of the overpayment in the limited circumstances set out in s 90AA(3). Further, the express limitation of the jurisdiction of the Court serves to confirm that legislative intention. By effectively barring any other recovery action by a taxpayer, and limiting the Court's jurisdiction to entertain proceedings, ss 90AA and 92A serve to enhance the operation of that scheme.[62]

83 The judge based her conclusion that the objection and refund regimes are the only means by which a taxpayer can establish that an assessment made under the Act is excessive by reference to the statutory text.[63] Her Honour noted that the regime established under the Act 'operates on the basis that the making of the assessment gives rise to a liability to pay the whole of the amount assessed'[64] and that, applying Commissioner of State Revenue v Gas Ban Pty Ltd (in liq),[65] (where assessments were made with respect to payroll tax) as a consequence of an assessment, a fixed and certain amount becomes due and payable, an assessment being neither tentative nor provisional. The judge went on to say that once an assessment is made, it gives rise to a statutory debt to pay the amount assessed regardless of whether an objection is later successfully made. Moreover, the Act specifically allows for refunds to be sought through application to the Commissioner and for proceedings to be commenced after refusal through the s 90AA process and in accordance with its stipulated time limits. The judge said:

In my view, as a matter of construction, the scheme of the LTA 1958 is such that once the assessment has been made, the amount so specified will become due and owing as the proper tax on the date specified for payment. That remains the position even if the assessment is challenged and later found to be incorrect. A person who is dissatisfied with an assessment may serve an objection on the Commissioner, seeking to establish that the assessment is excessive and that an overpayment has resulted, but the fact that an objection is pending does not interfere with or affect the assessment and the tax may be recovered on the assessment as if no objection had been received. Unless and until that assessment is set aside, or altered or varied, or an amended assessment issues, the taxpayer remains liable for the amount of land tax assessed.

Further, in circumstances where a person claims to be entitled to a refund or recovery of land tax, it is also open to the person to make application under s 90AA for a refund of the payment but such application must be lodged with the Commissioner within three years after the payment was made. If an application is lodged, the question of whether or not an amount has been overpaid is one for the Commissioner to determine. In the event that the Commissioner finds that an amount has been overpaid, he must refund it or apply it in the manner directed under s 90AA(6). If the Commissioner determines to refund an amount, that amount is payable from the Consolidated Fund, which is appropriated to the extent necessary. Proceedings, including proceedings brought by way of judicial review, seeking a refund or recovery of an amount of tax paid under, or purportedly paid under, the LTA 1958 may be brought but only in the limited circumstances identified in s 90AA(3), save in the case where the claim is made by reason of the invalidity of a provision of the Act. The limitation of the Court's jurisdiction to prevent it entertaining proceedings of a kind to which s 90AA(1) applies, except as provided in that section, further confirms the limited scope for bringing any collateral challenge or recovery action.[66]

84 The judge placed particular emphasis upon the legislative history and extrinsic materials in relation to the insertion of s 90AA in 1993[67] which imposed a clear temporal limit upon a taxpayer's ability to make claims and bring proceedings seeking refunds, as the relevant Minister said, to 'provide certainty and finality to Victoria's revenue collections'.[68] Her Honour emphasised the express limitation of the Court's jurisdiction under s 92A of the Act[69] and the interpretation given by this Court in Gas Ban to s 96(2) of the Taxation Administration Act 1997, a similar provision to s 90AA, to the effect that it was intended to exclude the possibility of judicial review.[70]

85 The judge also emphasised the closing words of s 19, namely 'the validity of an assessment shall not be affected by reason only that any of the provisions of this Act have not been complied with'. These words reflect those relied upon in Futuris as generally protecting an assessment from a challenge based on judicial review; this is discussed below.[71]

86 The judge further emphasised s 20 of the Act, in the context of the statutory scheme, as indicating the conclusiveness of assessments made by the Commissioner.[72] Seen as part of the evidence of legislative intention, she considered that s 20 demonstrates that a taxpayer's liability for the whole of the amount assessed arises from the assessment and remains so unless altered or varied. She said:

Where an assessment under the hand of the Commissioner is produced, s 20 of the LTA 1958 provides that the assessment is conclusive evidence of the due making of the assessment and that the amount and all of the particulars of the assessment are correct. That is so, even though there may be other material available that casts doubt upon the correctness of the assessment. But until that assessment is altered or varied or set aside, or an amended assessment is made, the scheme of the Act is that the assessment prevails and the taxpayer remains liable for the whole of the amount assessed. This approach is confirmed by s 19, which specifically provides that the 'validity of an assessment shall not be affected by reason only that any of the provisions of the Act have not been complied with'.

If a taxpayer were permitted to challenge the amount of land tax assessed under the LTA 1958 for the 2002 year, outside of the objection regime, and to recover the amount of the alleged overpayment by a separate proceeding for money had and received, the integrity of the statutory scheme would be distorted. Perhaps most importantly, if the taxpayer were successful, the assessment issued by the Commissioner would no longer reflect the amount of tax actually payable.

In the present case, the plaintiff seeks to take the matter outside of the statutory scheme. It argues that the amounts it overpaid 'by mistake' to the Commissioner are not relevantly to be characterised as 'dut[ies] of land tax' under s 6 or 'tax on land' under s 8 of the LTA 1958. Further, it says that the 'conclusive evidence' provision in s 20 operates only where there has been something which answers the statutory process of an 'assessment' and, as the plurality of the High Court noted in Futuris, 'conscious maladministration of the assessment process may be said also not to produce an "assessment" to which s 175 applies.' In this regard, the plaintiff now contends in its proceeding brought by way of Originating Motion, that as a result of the matters set out in the Commissioner's August 2013 correspondence, there has been maladministration by the Commissioner. But no contention is made to the effect that at the time the various assessments of land tax were made in each year between 1990 and 2002 there was any 'bad faith' or 'lack of good faith' in the process of the making of the assessments such as would found jurisdictional error.[73]

87 These remarks were made by the judge in the context of her consideration of the common law proceedings for restitution. However, to foreshadow what is discussed below, ACN relies on the omission of any detailed examination of the scope and purpose of s 19 from the judge's initial presentation of the statutory scheme, and the judge's observations that if ACN were permitted to raise a challenge outside of the objection regime 'the integrity of the statutory scheme would be distorted' and that ACN sought to 'take the matter outside of the statutory scheme', as indicating that her Honour failed to treat the power to amend assessments under s 19 as integrated within the statutory scheme. Alternatively, ACN submits that these remarks indicate that the judge approached the submissions it made on the amendment power under s 19 after having already determined that the statutory scheme for the recovery of overpayments lay solely in the objection and refund regimes before taking into account the scope and purpose of s 19. This is said to be apparent in the structure of her Honour's reasons. As noted above,[74] the judge identified the issue of whether the power under s 19 could be enforced by mandamus as Issue 3 after having considered, via Issue 1, whether the objection and refund regimes were the only means by which recovery of overpayments could be pursued.

88 The judge went on to conclude that under the statutory scheme an assessment creates a debt due to the Crown and payments made to the Commissioner to relieve that indebtedness are properly made, including those made by ACN during the 1990-2002 land tax years. She later used these observations to deny that ACN made any payment under any operative mistake.[75] She said:

In my view, each of the arguments advanced by the plaintiff to the effect that the amounts it paid were not tax because there was no valid assessment runs contrary to the statutory scheme established. For any of them to gain traction, the plaintiff must first establish that the assessment is excessive. Here, the amounts that were assessed and paid are common ground. Under the statutory scheme, once an assessment is made and the date for payment falls due, there is a debt due to the Crown. In each of the relevant land tax years when payments were made by the plaintiff, it did so because it was indebted to the Commissioner in the amount of land tax so assessed and the payment so made discharged that indebtedness.[76]

89 The judge also considered other forms of taxation legislation where the objection regime has been held to be exclusive and exhaustive.[77] On Issue 1 she concluded that there was no scope for ACN to pursue its claim for restitution given the exclusivity of the objection and refund regimes under the Act.[78]

90 The judge went on to accept the Commissioner's contention that there was no relevant mistake made by ACN when paying the assessments. She noted that the mistake as alleged by ACN in its statement of claim was that payment had been made 'in the mistaken belief that the land tax liability as assessed by the defendant in the assessments for the 1990-2002 years was properly due and payable to the defendant under the LTA 1958, and that it was legally obliged to make those payments'.[79] The judge considered that there was no such operative mistake; rather, each of the payments made during the 1990-2002 land tax years amounted to a payment to discharge a lawful obligation; namely, land tax assessed under the Act. Once the assessment issued, the land tax so assessed became due and payable on the date stated, pursuant to s 57,[80] as a debt due to the Crown, pursuant to s 39,[81] and recoverable by the Commissioner on behalf of the Crown, pursuant to s 59,[82] regardless of whether any objection or appeal was pending. She said:

I agree with the Commissioner's contention. For the reasons advanced by the Commissioner, I am not satisfied that there was any operative mistake at the time the various payments were made. Once the assessments were made by the Commissioner (and the date(s) specified for payment arrived), the plaintiff became indebted to the Crown for the sum(s) assessed. As and when the payments were made, they were made in the discharge of a legal obligation to pay, and that indebtedness was discharged upon the payments being made by the plaintiff. In circumstances where those assessments have not been successfully objected to, or amended or withdrawn and re-issued, that remains the position. Accordingly, I am not satisfied that there was any operative mistake at the time the respective payments were made by or on behalf of the plaintiff.[83]

91 Having arrived at this conclusion, it was strictly unnecessary for her Honour to consider whether, if ACN could seek to recover the payments it made by means of a proceeding for restitutionary relief, any limitation period applied. However, in summary, she went on to consider the potentially applicable limitation periods and determined that s 90AA would shut out the restitution proceeding (indeed, would shut out both of ACN's proceedings). She also concluded that the twelve-month period under s 20A of the Limitations Act did not apply, but that, even if it did, ACN could not take the benefit of postponement under s 27 of the Limitations Act because with reasonable diligence it would have been able to discover the duplication error.

Issue 2 - Would a limitations provision bar the proceedings for restitution?

92 With respect to the limitation question, Issue 2,[84] the judge referred to the clarity of the terms in which s 90AA is drafted,[85] as plainly imposing a three-year limit on applications for a refund, a requirement which was not satisfied here:

In my view, the intention of s 90AA is plainly to place a three year time limit on the making of tax refunds and to confine the scope for making application therefor. That intention is manifest from the express words used in the section and is confirmed by the second reading speech. The wording of s 90AA(2) is clear. The section applies in circumstances where 'a person claims to be entitled to receive a refund of or to recover tax paid under, or purportedly paid under', the LTA 1958. That is, the terms in which the provisions of s 90AA are expressed make clear that s 90AA(2) applies 'if' a person claims to be entitled to a refund, unless the claim is made by reason of the invalidity of a provision of the Act (s 90AA(5)). In that event, an application (in the prescribed form) must be lodged with the Commissioner within the three year period. In the present case, no application for a refund was made within the time limited by s 90AA(2).[86]

93 The judge noted that s 90AA provided that 'proceedings' for the refund or recovery of tax 'must not be brought' except as provided in s 90AA, that section providing a clear procedure and time limits for the taking of steps for the recovery of payments, steps that were not taken here. She also rejected the view that the alternative limitation provision, under s 20A of the Limitations Act[87] applied:

If s 90AA(1) does apply to this proceeding then it is foreclosed from being pursued. That is because the proceeding is not one brought against the Commissioner in the limited circumstances outlined in s 90AA(3). Importantly, s 20A(1) of the Limitation Act does not address the time period for the making of an 'application' to the Commissioner for a refund. That period is fixed by s 90AA(2) of the LTA 1958. As I have said, under the scheme established by the LTA 1958, a 'proceeding' may only be issued where an application for a refund has been lodged under s 90AA(2) and the Commissioner has not within 3 months refunded the amount or refused to make a refund. It is only in the event that such a proceeding is capable of being commenced against the Commissioner that s 20A(1) could supply the relevant limitation period for the commencement of a 'proceeding' for the recovery of money paid by way of tax or purported tax.

Accordingly, I am not satisfied that s 20A is enlivened in the present circumstances. ... [88]

94 Furthermore, even if s 20A[89] did apply in the circumstances, it being the more specific, and later, section addressing the situation where an amount attributable to tax is paid under a mistake, the judge was not satisfied that ACN had demonstrated a basis for postponing the commencement of the relevant limitation period under s 27.[90] As mentioned,[91] if s 27 did apply, ACN sought to postpone the commencement of the limitation period until 23 March 2012 when Ngo was first informed of the duplication error by the Commissioner. The judge considered that for ACN properly to rely upon s 27, it had to establish two elements: (1) that the proceeding was one 'for relief from the consequences of a mistake' and (2) that it could not 'with reasonable diligence' have discovered the mistake.

95 With respect to the character of the mistake relied upon, the judge observed that in this context ACN characterized the operative mistake as a 'mistake in the assessments'[92] as opposed to a mistake that the land tax liability was properly due and payable and that it was legally obliged to make the payments, as the mistake had been characterized in ACN's statement of claim.[93] As she put it:

It will be noted that the relevant mistake the plaintiff contends for under s 27 differs in formulation from that advanced generally on its claim for restitutionary relief. For the purposes of s 27, the plaintiff says that the relevant mistake lies in the assessments themselves; in effect, that the plaintiff could not, with reasonable diligence, have discovered that a duplicate property was included in the assessments.[94]

96 The question of the character of the mistake is something to which we shall return.[95] This will involve examining the manner in which the judge characterized the mistake relied upon by ACN as a mistake that the land tax liability was properly due and payable (which she rejected because the Act operated so as to give rise to a legally enforceable debt) by contrast with characterizing the mistake under which ACN paid the excess amount so as to reflect the Commissioner's duplication error which we have found was operative in the 1990-2002 land tax years.[96]

97 In addressing the question of the applicable limitation period governing recovery (had recovery been possible) the judge addressed the question of whether there had been a mistake in the assessments in the relevant years. She emphasized that there was little evidence in relation to the initial acquisition of the two properties by ACN and no evidence about what returns ACN furnished for the purposes of assessment. The judge concluded that there was no evidence whether the same duplication error occurred in the rate notices of the Council and therefore whether a proper comparison would have revealed the error. Her Honour appeared to be critical of ACN for relying solely on the face of the assessments as in themselves failing to provide any indication of error. The judge said:

I have already outlined the evidence adduced from Mr Davis and Mr Ngo on behalf of the plaintiff. As noted earlier, neither of them has personal knowledge of the events that took place when either the 65 Albany Rd or the 2 Ottawa Rd properties was purchased and the properties were first assessed for land tax. There is little in the way of evidence about what transpired when the plaintiff became the owner of both properties from 1988. There is, for example, no evidence about what information the plaintiff furnished to the Commissioner under ss 14 and 15 of the LTA 1958 for the purposes of the assessment and levying of taxation, and the assessments themselves have not been located. But Mr Davis has exhibited copies of the Assessment Reports issued by the SRO for the 1983-2001 land tax years.

It is common ground that the valuation used for land tax purposes in each relevant year from 1993 was essentially the same as that which was used by the City of Stonnington for municipal purposes. Mr Fitzgerald, the City of Stonnington valuer, has confirmed that the municipal valuations for 2 Ottawa Road conducted from October 1992 onwards encompassed both Lot 1 Lodge Plan 27424 and Lot 1 Title Plan 598039. Once apprised of this, the SRO informed the plaintiff that the property described on the land tax assessments as '65 Albany Rd' was determined to be a 'duplicate property'.

For those land tax years where assessments are available, from 2002 through to 2007, they record in each case the unimproved (or site) value of each of 2 Ottawa Rd and 65 Albany Rd respectively. For example, in the case of the land tax assessment for the 2002 year, the unimproved (or site) value specified for 2 Ottawa Rd and for 65 Albany Rd is $2,010,000 and $1,830,000 respectively. The 'Land Id/References' shown on the 2002 assessment convey the erroneous impression that 2 Ottawa Rd relates to Lot 1 on Lodge Plan 27424 only. Once one is apprised of the fact that the unimproved (or site) value specified for 2 Ottawa Rd actually pertains to both Lot 1 on Lodge Plan 27424 and Lot 1 on Title Plan 598039, it is difficult to make sense of the relative values for 2 Ottawa Rd and 65 Albany Rd as recorded on the assessment. When I raised this with the parties, however, I was informed that I should simply proceed on the basis that 65 Albany Rd is the duplicate property.[[97]]

There is no evidence before the Court as to whether the same 'duplicate property' error was made in the City of Stonnington rate notices for the relevant years. This matter is not addressed in the affidavits of either Mr Davis or Mr Ngo filed on behalf of the plaintiff. The Commissioner focussed on this aspect in his written submissions, contending that a landowner could, with reasonable diligence, discover what land it owns. He argued that the land owner could also, with reasonable diligence, ascertain what value its land has been given by the local municipal council, discover by reference to what value the Commissioner had assessed its land for land tax purposes, and compare the two.

The plaintiff did not seek to adduce any additional evidence by way of response to the Commissioner's submission. Rather, it simply relies on the fact that the duplicate property error is one that is not readily apparent on the face of the assessment and contends that is sufficient to make good its reliance on s 27.[98]

98 Ultimately, the judge came to the conclusion that ACN had not discharged the burden of proof which fell upon it to establish that it could not, with reasonable diligence, have discovered the fact that the assessments for the 1990-2002 land tax years reflected the Commissioner's duplication error.[99] She said:

The starting point for evaluating the competing arguments is that the limitation period specified under s 20A applies unless the plaintiff demonstrates that there is good cause under s 27 for postponing the commencement of the period because the plaintiff could not with reasonable diligence have discovered the mistake. For present purposes, the concept of reasonable diligence requires some assessment of that which an ordinarily prudent owner of a valuable property would do upon receipt of a land tax assessment having regard to all the circumstances. The plaintiff owned at least two properties during the relevant period. The alleged 'overpayments' in question here for each of the tax years from 1990 to 2002 are significant amounts. The evidence given by Mr Davis is that he has been performing his role with the plaintiff and Streetriver since November 1993 and says he has been 'closely involved in the land tax affairs of both these companies'. As neither he nor Mr Ngo was involved in the land tax affairs of the plaintiff at or around 1988 when both properties came under common ownership, they cannot give evidence from their own knowledge about the events at that time. No mention is made of whether, prior to November 1993, anyone else was involved in the plaintiff's land tax matters. To the extent Mr Davis's evidence addresses the period from late 1993 when he became actively involved in the land tax affairs of the plaintiff, he gives no account of what, if any, steps were taken regarding payment of the assessments.

Under s 27 of the LTA 1958, the plaintiff bears the onus of proof. In my view, the evidence given by Mr Davis, and Mr Ngo, based on information and belief after conducting an examination of the financial and business records of the plaintiff, says little of substance about whether or not 'from 1988' the plaintiff could, with reasonable diligence, have discovered 'the mistake in the assessments'. In the circumstances, I am not satisfied that the plaintiff has discharged the burden of demonstrating that it could not, with reasonable diligence, have discovered the fact that the assessments of land tax for the years 1990 to 2002 inclusive erroneously included a duplicate property.[100]

99 Accordingly, as no basis had been demonstrated for postponing the limitation period under s 27, even if s 20A of the Limitations Act applied, the proceeding was barred as it was not commenced within 12 months after the date of payment. If ACN was unable to take the benefit of the postponement under s 27, it was also of little consequence whether the six year limitation period under s 5(1) of the Limitations Act was applicable because the proceeding was not brought within six years from the date of payment.[101]

Issue 3 - Can the power under s 19 be enforced by mandamus?

100 ACN submitted before the judge that the power the Commissioner has under s 19 to issue amended assessments to ensure the completeness and accuracy of an assessment gives rise to a duty upon the Commissioner in the circumstances of the case. Those circumstances included the receipt of a request from ACN to amend its assessments for the 1990-2002 land tax years and the fact that the Commissioner had made the duplication error during each of those years. The judge noted that the Commissioner did not admit that he made the duplication error during the 1990-2002 land tax years.[102]

101 ACN argued before the judge, as it did on the appeals, that the duty to which s 19 gives rise is to: (1) issue amended assessments for the 1990-2002 land tax years in order to assess accurately the land tax that is properly payable by ACN in those years in respect of the two properties; and (2) refund the amount of any overpayment of any land tax to ACN. It argued that the power under s 19 is unlimited as to time, it being exercisable 'from time to time', and that it must necessarily include an implied power of appropriation to honour the obligation to refund.

102 The Commissioner denied before the judge, as he denies on the appeals, that s 19 gives rise to a duty; rather, he argues, s 19 confers a discretion and while mandamus can be ordered to make a public official exercise a discretion it cannot be used to control the exercise of that discretion by directing that the power be exercised in a particular manner. The Commissioner submitted that, in any event, if there was a duty upon him to exercise the discretionary power under s 19, he did so by making the decision not to make any amendments to the assessments for the 1990-2002 land tax years, which he communicated to ACN by the letter of 15 August 2013.[103]

103 The judge approached the question of the scope and operation of s 19 by acknowledging the principle in Julius v Lord Bishop of Oxford[104] to the effect that the conferral of a power may in some circumstances 'couple the power with a duty', quoting from Lord Cairns LC:

[T]here may be something in the nature of the thing empowered to be done, something in the object for which it is to be done, something in the conditions under which it is to be done, something in the title of the person or persons for whose benefit the power is to be exercised, which may couple the power with a duty, and make it the duty of the person in whom the power is reposed, to exercise that power when called upon to do so. Whether the power is one coupled with a duty such as I have described is a question which, according to our system of law, speaking generally, it falls to the Court of Queen's Bench to decide, on an application for mandamus.[105]

104 The judge then examined how the Julius principle had been applied by the High Court in Royal Insurance. Much turns on identifying the proposition for which Royal Insurance is authority. This depends upon an understanding of the reasoning of Brennan J with whose judgment Toohey and McHugh JJ agreed, together forming the majority. This is a matter to which we shall return in detail but it is also important, first, to see how the judge approached Royal Insurance.

105 The section at the heart of Royal Insurance conferred a power upon the Comptroller of Stamps to refund overpayments of stamp duty. Section 111(1) of the Stamps Act 1958 ('the Stamps Act') provided:

Where the Comptroller finds in any case that duty has been over-paid, whether before or after the commencement of the Stamps Act 1978[[106]] he may refund to the company, person or firm of persons which or who paid the duty the amount of duty found to be overpaid.[107]

106 The statutory successor to the Comptroller of Stamps was the Commissioner of State Revenue.[108] The Commissioner made a finding that stamp duty in the amount of $1,907,908.10 had been overpaid but decided not to make a refund.[109] The question of whether the power to refund gave rise to a duty, in the circumstances of the case, was critical. The judge understood the reasons of Brennan J to answer that question in the negative. Her Honour said:

His Honour found that s 111(1) in terms 'confers a discretionary power on the Commissioner to refund overpaid moneys ... but creates no duty to do so. He said 'no enforceable obligation to make the refund arises merely from a finding that there has been an overpayment' and the Commissioner 'is under no duty to make a refund unless there be an antecedent liability to do so' and unless such a liability exists, 'there is no duty to exercise the power conferred by s 111(1) nor any authority to do so.' His Honour then posed the question of whether, if the Commissioner is under a liability to refund an amount which she has found to have been overpaid under s 111(1), 'can she be compelled to perform her duty to do so?' Applying the approach stated by Lord Cairns LC in Julius, Brennan J said:

The Commissioner is a public officer vested with a power to be exercised for the purpose, inter alia, of discharging her liabilities. When the power exists and the circumstances call for the fulfilment of a purpose for which the power is conferred, but the repository of the power declines to exercise the power, mandamus is the appropriate remedy even though the repository has an unfettered discretion in other circumstances to exercise or refrain from exercising the power. Mandamus will go where there is a duty to pay money. In this case, there is no residual discretion in the Commissioner to refrain from making a refund in the exercise of the powers under s 111(1) once she finds that there has been an overpayment and there is a legal liability to refund the amount found to have been overpaid.

Thus the position was that while s 111(1) conferred a discretionary power on the Comptroller to refund money overpaid, it created no duty to make a refund. However, once the Comptroller made a finding that the duty had been overpaid, she had no residual discretion to refrain from making a refund under s 111(1), and was under a legal liability to refund.[110]

107 Her Honour went on to consider other authorities relied upon by the parties, including Commissioner of Taxes v Tourism Holdings Ltd;[111] Commonwealth Agricultural Service Engineers Ltd (in liq) v Commissioner of Taxes (SA);[112] and Boyded Industries Pty Ltd v Commissioner of Taxation.[113] She rejected the view that the Commissioner is under a duty to exercise the power under s 19 on the basis of two threads of reasoning: (1) that there had been no operative mistake in the circumstances of the case;[114] and (2) on the basis of the conclusions at which she had already arrived, namely that the objection and refund regimes were exclusive and exhaustive.

In my view, when the legislative framework in place under the LTA 1958 is examined, it is clear that 'the intention of the legislature as revealed in the language of the statute' (to adopt Brennan J's language) is not to place the Commissioner under a duty to exercise the power to amend in s 19. The scheme of the Act has been discussed at length earlier in these reasons. It provides for a taxpayer who is dissatisfied with an assessment to lodge a written objection within 60 days of the assessment. The taxpayer carries the burden of proving that the assessment is excessive. If the taxpayer is dissatisfied with the Commissioner's decision on an objection he may seek a review in the Tribunal or an appeal to this Court. The objection route is the mechanism the LTA 1958 provides for a taxpayer to establish that an assessment is excessive, and strict time limits for doing so are imposed. In the event of an assessment being altered on objection or case stated or appeal, s 38(2) provides for due adjustment to be made, for which purpose amounts paid in excess shall be refunded, and amounts short-paid shall be recoverable as arrears. Thus, s 38(2) operates as an implied appropriation of the moneys required to effect any refund.

Where a taxpayer contends that it has overpaid tax, the LTA 1958 also provides another means for the taxpayer to claim a refund or to recover tax paid under, or purportedly paid under, the Act. Under s 90AA(2), the taxpayer is required to lodge, within three years after the payment was made, an application in the prescribed form for the refund of the payment. If, after such an application is lodged the Commissioner finds that an amount has been overpaid, then under s 90AA(6) the Commissioner must refund the overpaid amount or apply the overpaid amount against any other liability of the applicant (as specified in subs (6)(d)(i)) and refund the balance. If the Commissioner determines to refund an amount, then subs (7) provides for the Consolidated Fund to be appropriated accordingly. In this way, s 90AA enables a taxpayer who claims it has overpaid tax to secure a refund from the Commissioner. But if the taxpayer wishes to exercise the right conferred by s 90AA(2), it must do so within the three year period. Once the prescribed three-year period expires, the position is effectively the same as Mildren J described in Tourism Holdings, namely that 'nothing can be done' and '[t]he matter is closed'.

When introducing s 90AA, the Treasurer explained that the three year time limitation 'was designed to provide certainty and finality to Victoria's revenue collections.' That objective would not be promoted if it were open to a taxpayer who had not availed itself of either the objection route or the application for refund route, within the prescribed times, to effectively challenge the assessment at any later date and seek to recover an overpayment by seeking mandamus to compel the Commissioner to exercise his power under s 19 to amend an assessment. Furthermore, the bringing of such a proceeding would likely contravene the prohibition in s 90AA(1) against bringing proceedings (including for mandamus and similar forms of judicial review) for the refund or recovery of tax paid under or purportedly under the LTA 1958 except as provided in s 90AA. There is also real doubt about whether the Court would have jurisdiction to entertain such a proceeding given the limitation on its jurisdiction imposed by s 92A.[115]

109 Focussing specifically on s 19, the judge emphasised the discretionary nature of the power conferred:

When [the] s 19 power was introduced, it conferred on the Commissioner the express power 'to do what otherwise he could not have done' (to adopt the words of Murray CJ in the Commonwealth Agricultural Service Engineers case), namely to be able to issue an amended assessment. Further, the power was, and has at all times been, expressed in terms connoting a discretion on the part of the Commissioner to amend and any amendment is predicated on it being such 'as he thinks necessary' to ensure its completeness and accuracy. The language used does not suggest that the section was intended to confer any right on the taxpayer. The word 'may' is to be understood in its ordinary and natural sense of being permissive and facultative only. When coupled with the notion that the power is to be exercised for making such alterations or amendments 'as [the Commissioner] thinks necessary', the discretionary nature of the power is confirmed.[116]

110 She took the view that the place of s 19 within the context of the statutory scheme as a whole indicated that it did not give rise to a duty:

In the Royal Insurance case, in dealing with the discretion conferred by s 111 of the Stamps Act 1958, Mason CJ referred to the earlier decision of the Court in Ward v Williams and said:

But, as the court went on to point out in Ward v Williams, the question whether a public officer, to whom a power is given by facultative words, is bound to exercise that power upon any particular occasion, or in any particular manner, is to be solved from the context, from the particular provisions, or from the general scope and objects of the enactment conferring the power.

The plaintiff also relied on these observations of Mason CJ as confirming that in certain circumstances, a power, although expressed in discretionary language, will become a duty.

When s 19 is viewed in the context of the scheme of the LTA 1958 as a whole, and against the background of the objection procedure and associated appeal processes, the conferral of a separate right on the taxpayer to apply for a refund, the discrete timeframes specified for a taxpayer to use those processes, and the limitation on both the ability of a taxpayer to bring proceedings outside that regime and the Court's jurisdiction to entertain them, one gains the clear impression that s 19 was not intended to confer any right on the taxpayer or to impose on the Commissioner any obligation that the taxpayer could enforce in a court of law.

Having found that there is relevantly no duty imposed on the Commissioner to amend, there is no basis for mandamus or the like to issue.[117]

111 Having rejected ACN's principal submission, the judge turned to consider ACN's challenge to the actual refusal by the Commissioner to amend the assessments,[118] namely, that it amounted to conscious maladministration of the Act because the Commissioner: (1) must have known or reasonably suspected that the assessments were wrong in a fundamental respect given that '65 Albany Road' was known to be a duplication property; and (2) there was therefore no authority for him to retain the wrongfully demanded moneys. She rejected ACN's challenge in express reliance on her earlier conclusion that the power under s 19, viewed in the context of the statutory scheme as a whole, did not give rise to a duty. She sought to distinguish Royal Insurance in a number of respects, most especially the significance of the Commissioner's finding in that case that an overpayment had been made and that the payments were not there made in response to assessments issued. Ultimately she held that the limited circumstances in which the Act permitted challenges to be brought, as evidenced in particular by s 90AA, indicated that there was no room for a separate challenge based on s 19 to be brought:

I am not persuaded that the conduct or decision of the Commissioner evidences 'a fundamental error' or demonstrates a 'fundamental misunderstanding' of the Commissioner's role under the Act. That conclusion is informed in large part by my finding that when the power conferred by s 19 is viewed in context of the scheme of the LTA 1958 as a whole, the Commissioner was not under any duty to exercise his power to amend. It was, as the Commissioner contends, a power that fell to be exercised by the Commissioner in his discretion, having regard to the subject matter, scope and purpose of the LTA 1958 as a whole.

The present case is very different from the Royal Insurance case. The legislative framework that applied in that case was quite different from the present one in some important respects. First, as the Commissioner points out, the statutory scheme under the Stamps Act 1958 was a self-assessment regime rather than one of assessment by the Commissioner, based on information provided by the taxpayer, giving rise to a debt due to the Crown. Secondly, under the Stamps Act 1958, there was no process or mechanism by which a taxpayer could later object to the (self) assessment so made. Thirdly, under the Stamps Act 1958, there was no time limit on the making of an application for refund of an overpayment nor was there any limitation imposed on the means or method by which such a refund might be sought. Fourthly, there was no express limitation on the power of the Court to entertain a proceeding for the refund or recovery of the overpayment (including a proceeding at common law or by way of mandamus or other form of judicial review) save in specified circumstances. Further, and perhaps more importantly for present purposes, the Comptroller made a finding that the duty sought to be recovered had been overpaid. The High Court found that, having done so, the circumstances of the case were such that she had no residual discretion to refrain from making a refund under s 111(1), and the Comptroller was under a legal liability to refund.

In the Royal Insurance case_,_ when dealing with the taxpayer's submission that in the context of the Commissioner's duty to investigate under s 111, there was a duty to refund once overpayment was found to have taken place, Mason CJ observed that:

On the assumption that the section creates a duty to investigate, I do not consider that the existence of such a duty leads to the existence of an obligation to refund once overpayment is established. No doubt there will be circumstances in which it will be a proper response, indeed the only proper response, to refund the overpayment but that will not always be the case.

His Honour said he could not accept the proposition that, once overpayment has been found to have been made, 'the discretion must be exercised by making a refund.' He added that '[a]n action which is time barred is another illustration of circumstances in which refusal to make a refund would be justified.'

In my view, it does not follow from the fact that the Commissioner decided to exercise the discretion conferred on him by s 19 that he is bound to exercise the discretion in any particular way. On the contrary, once consideration is given to the legislative framework in place under the LTA 1958, and regard is had to the intention of the legislature as revealed in the language of the statute, and in particular the limited circumstances in which the legislature intended that a person claiming to be entitled to a refund or recovery of tax could bring proceedings, it is clear that it was open to the Commissioner to form the view he did. In reaching the decision to not make any amendment to the assessments, the Commissioner determined that, in his view, no amendment was necessary. Such a view demonstrably accords with, and promotes, the legislature's clear intention that any person who claims to be entitled to receive a refund or to recover tax paid under, or purportedly under the LTA 1958 must make application to the Commissioner within three years after the payment was made.

Accordingly, the proceeding for mandamus will be dismissed.[119]

Issue 4 - Would a limitations provision bar mandamus?

112 Given the judge's rejection of ACN's claim based on s 19 it was strictly unnecessary for her Honour to consider whether, if a s 19 claim could be brought, it was nevertheless barred because of the expiration of time. However, she considered the submissions of the parties on limitations, in the context of the mandamus proceeding, and determined that, substantially for the reasons she gave with respect to the limitations issue in respect of the restitution proceeding (Issue 2), s 90AA would operate to prevent the mandamus proceeding being brought.

113 The judge observed, by reference to the terms of the relief sought by ACN in its amended original motion,[120] that

the application for mandamus is both a 'proceeding' for the purposes of s 90AA and one brought for 'the refund or recovery of tax' that was 'paid under, or purportedly under' the LTA 1958. As no application for the refund of the payment(s) was lodged within three years after payment was made, as required by s 90AA(2), the process that might otherwise have enabled the plaintiff to bring proceedings was not enlivened. Accordingly, s 90AA(1) operates to bar the plaintiff bringing the proceeding.[121]

114 Alternatively, the judge held that if s 90AA of the Act did not apply, then the 12 month limitation period prescribed by s 20A(1)(a) of the Limitations Act would apply and could only be postponed under s 27 if ACN, exercising reasonable diligence, could not have detected the mistake before 23 March 2012 (if there was an operative mistake, which the judge had rejected):

If, contrary to my view, s 90AA did not operate to bar the plaintiff bringing the proceeding, then s 20A(1) likely would, if the element of 'mistake' were made out. Once again, as framed, the application for mandamus is both a 'proceeding' for the purposes of s 20A and one brought for 'the recovery of money paid by way of tax or purported tax' or 'by way of an amount that is attributable to tax or purported tax under a mistake (either of law or fact)'. The relevant limitation period is the period of 12 months prescribed in s 20A(1)(a). This is because the proceeding for mandamus is not one brought under s 90AA of the LTA 1958, so there is no 'other Act' that relevantly could provide for a longer period. The proceeding was not commenced within 12 months after the date for payment of the respective assessments. In that event, there is potential for s 27 to apply. If, contrary to my view, the proceeding is to be characterised as one for relief from the consequences of a 'mistake' then for the reasons discussed earlier, I am not satisfied that the plaintiff has demonstrated that it could not, with reasonable diligence, have discovered the mistake at an earlier point.[122]

115 Similarly, if a six year limitation period applied under s 5(1) of the Limitations Act, the mandamus proceeding was brought out of time and ACN could not take the benefit of the postponement under s 27 for the reasons the judge had already given.

116 In the restitution proceeding, ACN sought interest on the excess amount, calculated on a compound basis, for the loss of the use of those funds for the respective periods. The interest claimed was said to be:

calculated by reference to what return, or what savings, the plaintiff could have achieved had it had the use of these monies over that time or, alternatively, by reference to the benefits, or savings, that the defendant has derived, and continues to derive, from the use of these funds over this period.[123]

117 The sum of compound interest alleged to be due was $632,732.[124]

118 The judge did not arrive at a final conclusion on the question of whether ACN would have been entitled to compound interest if it had been successful in its proceedings for restitution. It was not necessary for her Honour to arrive at a final conclusion given that she had determined to dismiss the proceeding.

119 With respect to the mandamus proceeding, the judge remarked that ACN accepted at trial that it could not establish a right to compound interest under the mandamus case but claimed a right to simple interest under statute from the dates of payment pursuant to s 58 of the Supreme Court Act.[125] However, on the appeals, ACN claims compound interest in the mandamus proceeding but only from the date of the constructive refusal to amend the 1990-2002 assessments, namely, 3 December 2012.

120 The issues that the parties focused upon in the appeals can be identified as follows:

(1) What is the nature of the power to amend assessments under s 19?

(2) Did the Commissioner engage in conscious maladministration?

(3) What proposition does Royal Insurance stand for?

(5) Would an underlying restitution claim be made out?

(6) Which limitation period applies - s 90AA, s 20A or s 5(1)?

(7) Is the limitation period postponed under s 27?

121 As is apparent from our summary of the judge's reasons, the judge commenced her analysis by considering the proceedings for restitution and, having arrived at a set of conclusions about the statutory scheme in that context, then approached an examination of the power under s 19. There was a risk in this approach that the power to make amended assessments under s 19 could be construed narrowly so as to fit into a fixed regime for recovery. We consider that it is important to examine first the scope and operation of the power under s 19 to amend assessments to ensure accuracy because the problem arises against a background where the Commissioner expressly admitted that, for the 2008-2011 land tax years, he had issued inaccurate assessments to ACN.[126] While the Commissioner does not expressly admit the inaccuracy of the assessments for the 1990-2002 land tax years, we consider that it would be artificial to approach the claims with respect to the 1990-2002 land tax years in isolation without viewing those claims as related to the claims where the inaccuracy of the assessments was admitted. This gives a central focus to the proceedings for mandamus, which ACN submits is its primary case on the appeals, as it was at trial.

(1) What is the nature of the power to amend assessments under s 19?

122 The meaning of a statutory provision must be determined by reference to the language of the statute viewed as a whole. As the High Court acknowledged in Project Blue Sky Inc v Australian Broadcasting Authority,[127] the primary object of statutory construction is to construe a relevant statutory provision so that it is consistent with the language and purpose of all of the provisions of the statute. It is also necessary to give effect to every provision of a statute, and, where possible, to give meaning to every word of a provision.[128]

123 In our view, it is important that the power under s 19 to make amended assessments for the purposes of completeness and accuracy is construed as part of the overall statutory framework by which inaccurate assessments can be corrected. This is in accordance with the underlying 'duty of the Commissioner ... to collect the correct amount of tax, and 'not a penny more, not a penny less', as Mildren J endorsed in Tourism Holdings.[129] In our view, s 19 is one of the provisions, alongside the objection regime and the refund regime, that ensures the integrity and accuracy of the system of tax collection under the Act. The language of s 19 makes it plain that it is one of the integrity mechanisms of the Act; that is, it is one of the mechanisms for ensuring that the Commissioner collects the correct amount of tax and only the correct amount of tax.

124 The power is only enlivened when the Commissioner knows that an assessment is incomplete or inaccurate. More particularly, the power arises when the Commissioner 'thinks [it] necessary'[130] to make an alteration or addition to an assessment for the purpose of ensuring the completeness and accuracy of the assessment. In other words, the power is predicated upon the Commissioner knowing that he has wrongly collected taxes that were not otherwise due. The s 19 power does not circumvent the objection and refund regimes because, by contrast to those regimes, the s 19 power is only enlivened when the Commissioner knows that an assessment is incomplete and inaccurate. Thus understood, the s 19 power is a measure to ensure the integrity of the system of tax collection under the Act.

125 ACN submits that the judge should have concluded that the Commissioner has no residual discretion to decline to issue amended assessments under s 19 when the Commissioner knows that the amendments are necessary to ensure the completeness and accuracy of the assessments. It submits that the judge was wrong in failing to find that there could be circumstances in which the Commissioner would be required to exercise the power under s 19.

126 It is clear that the word 'may' when used in the conferral of a discretionary power does not preclude the breadth of that power being significantly confined to an extent that, in some circumstances, the power must be exercised. The purpose for which it is to be exercised, or the condition under which it is granted, may reveal that in some circumstances there is an obligation to exercise the power. As the plurality of the High Court said in Attorney-General (NT) v Emmerson,[131] in considering s 44(1)(a) of the Criminal Property Forfeiture Act (NT):[132]

There were differences of views in the courts below as to the width of the discretion covered by the use of the word 'may' in s 44 of the Forfeiture Act, governing the making of a restraining order. The condition upon which the discretion is granted under s 44(1)(a) arguably makes it clear that the discretion is of the type which must be exercised upon proof of the particular case to which the power to make a restraining order is directed. In the Court of Appeal, the appellants never contended otherwise. ... For the purposes of the first respondent's argument it may be assumed, without deciding, that the discretion given to the Supreme Court under s 44 is limited.[133]

127 In Emmerson the plurality relied upon International Finance Trust Co Ltd v New South Wales Crime Commission[134] which in turn relied upon Finance Facilities.[135]

128 Finance Facilities concerned the construction of s 46(3) of the Income Tax Assessment Act 1936-68 (Cth) which conferred a discretionary power on the Commissioner to allow a further rebate in certain circumstances.

Subject to the succeeding provisions of this section, the Commissioner may allow a shareholder, being a company that is a private company in relation to the year of income and is a resident, a further rebate ... if the Commissioner is satisfied that -

(a) the shareholder has not paid, and will not pay, a dividend during the period commencing at the beginning of the year of income of the shareholder and ending at the expiration of ten months after that year of income to another private company;

(b) where the shareholder has paid, or may pay, a dividend during the period -

(i) commencing at the beginning of the year of income of the shareholders; and

(ii) ending at the expiration of ten months after that year of income, to a company, being a private company in relation to the year of income of the company in which the dividend was, or may be, paid, the company has not paid, and will not pay, a dividend during the period -

(iii) commencing at the beginning of the year of income of the company in which the dividend has been, or may be, paid by the shareholder; and

(iv) ending at the expiration of ten months after that year of income, to another private company; or

(c) having regard to all the circumstances, it would be reasonable to allow the further rebate.

130 The High Court held that when any of the alternative circumstances specified in the section were met, the Commissioner was under a duty to exercise the power. This depended not on the abstract meaning of the word 'may' but on whether the particular context of the words and circumstances converted the word 'may' from that of an empowering or facilitative word to a word capable of having mandatory force. Windeyer J famously said:

Here the scope of the permission or power given is circumscribed. Conditions precedent for its exercise are specified as alternatives. The question then is, must the permitted power be exercised if one of those conditions be fulfilled?

This does not depend on the abstract meaning of the word 'may' but of whether the particular context of words and circumstance make it not only an empowering word but indicate circumstances in which the power is to be exercised - so that in those events the 'may' becomes a 'must'. Illustrative cases go back to 1663: R v Barlow. Today it is enough to cite Julius v Bishop of Oxford; and add in this Court Ward v Williams. But I select one other reference out of a multitude: Macdougall v Paterson. There Jervis CJ said in the course of the argument 'The word "may" is merely used to confer the authority: and the authority must be exercised, if the circumstances are such as to call for its exercise'. And, giving judgment, he said:

'We are of opinion that the word "may" is not used to give a discretion, but to confer a power upon the court and judges; and that the exercise of such power depends, not upon the discretion of the court or judge, but upon the proof of the particular case out of which such power arises.'

I consider that to be directly applicable to the present case. If the Commissioner, having considered the matter, is satisfied of facts out of which the power to allow a rebate arises, he cannot nevertheless refuse to allow it. That is obvious in the case of condition (c): and it seems to me to be so also in the case of the alternatives (a) and (b).[136]

131 In International Finance Trust, Hayne, Crennan and Kiefel JJ said of the Finance Facilities principle that it recognises that in many cases the terms on which a power is conferred will demonstrate that where the terms are satisfied the power must be exercised:

The principle applied in Finance Facilities Pty Ltd v Federal Commissioner of Taxation recognises that there are many cases where a statute confers a power on a court (and to that end uses the word 'may') but does so in terms that make plain that the authority thus given must be exercised upon proof of the particular case out of which the power arises. In the present case, the CAR Act[[137]] avoids the constructional difficulty that sometimes attends cases resolved by applying the Finance Facilities principle by saying that the Court must make a restraining order if the conditions for its making are established. But that does not deny that in every case where application is made for a restraining order the issue tendered for decision will be whether the relevant conditions are met. And the decision of an issue of that kind is an ordinary and unremarkable performance of the judicial function. Apart, then, from setting the relevant factual hurdle at the level of the existence of a reasonably grounded suspicion of criminal conduct, as distinct from proof of its commission, the provisions of s 10(3) of the CAR Act do not differ from any of a number of different statutory conferrals of jurisdiction upon courts which require the court to exercise a power if conditions prescribed for its exercise are met. ...[138]

132 ACN submits, on the strength of the Finance Facilities principle, that the particular context of words and circumstances make the 'may' in s 19 not only an empowering word but indicate when the power must be exercised. It points to the recognition that mandamus may be granted in order to compel the payment of public money and should ordinarily be granted where a public officer is refusing to comply with an obligation or where a public officer with discretionary powers does not exercise them according to law.

133 In Tourism Holdings the Court of Appeal of the Northern Territory[139] considered a somewhat similar amendment power conferred on the Commissioner of Taxes of the Northern Territory, s 97(1) of the Taxation (Administration) Act 1978 (NT):

The Commissioner may, at any time within a period of 3 years after the date of an assessment by him of duty, amend the assessment by making such alterations or additions to it as he thinks necessary.

134 An objection had been lodged against an assessment for stamp duty but the objection was made on behalf of a related company and not the company that had been assessed. When the mistake was identified, the Commissioner refused to extend time to permit the filing of a late objection on the ground that he had no power to do so. The taxpayer requested the Commissioner to issue an amended assessment. The Commissioner declined to consider to do so. At first instance the primary judge held that the Commissioner did have power to grant an extension of time in which to lodge an objection, from which the Commissioner appealed, but held that the Commissioner was not under a duty to consider the request to amend the assessment or exercise the discretion conferred by s 97(1). The Court of Appeal allowed the cross-appeal brought by the taxpayer with respect to the operation of s 97(1) and held that the Commissioner was obliged to consider whether to exercise the discretion. It emphasised that the duty of the Commissioner is to collect the correct amount of tax, and only the correct amount. Mildren J said:

The duty of the Commissioner is to collect the correct amount of tax, and 'not a penny more, not a penny less': see Lighthouse Philatelics Pty Ltd v Commissioner of Taxation (1991) 32 FCR 148 at 155.[[140]] Section 97(1) empowers the Commissioner to amend an assessment at any time within three years. The amendment may result in more tax being collected, or a refund, depending on the circumstances. If the Commissioner formed the view that a refund was warranted, it would plainly be his duty to amend the assessment and make the refund: see s 97(3).[141]

135 Mildren J pointed to the general principle of administrative law that a statutory power is to be exercised in accordance with its purpose, that is,

the principle of administrative law that every person entrusted with a discretion granted by statute must exercise it in accordance with law and in accordance with the purposes for which the discretion is given.[142]

136 He held that the purpose of the amendment power conferred under s 97(1) was to ensure that the amount assessed is correct, notwithstanding that no objection or appeal had been brought. He noted that the amendment power had an internal limitation period of three years:

The power conferred by s 97(1) is to be used by the Commissioner 'to make such alterations or additions to (the assessment) as he thinks necessary'. It is clear that the amendment may have the effect of either increasing or reducing the taxpayer's liability and in the latter case, the taxpayer is entitled to a refund: see s 97(3). If the amendment results in the taxpayer becoming liable to additional tax, the taxpayer has a further right of objection: see s 100(6). The purpose of the power is clearly to ensure that the correct amount of tax is collected, notwithstanding that there has been an assessment made which has not been appealed. The legislature clearly envisaged that mistakes could be made in the lodging of returns or by the Commissioner's officers in assessing the tax wrongly and conferred a power to ensure that these mistakes can be remedied within the three-year period. After that, nothing can be done. The matter is closed. This accords with the notion that the prime duty of the Commissioner is to collect the correct amount of tax: see Lighthouse Philatelics Pty Ltd v Commissioner of Taxation.[143]

137 Mildren J went on to conclude that it was necessary for the Commissioner to decide whether to exercise the discretion and, in doing so, to consider all relevant matters. He accepted that the Commissioner could refuse to exercise his discretion where, for example, he forms the opinion 'that there are no grounds for thinking that the decision was wrong'.[144] Thomas J adopted a similar approach on the cross-appeal, noting relevantly the words of Isaacs J in Agricultural Service Engineers that it 'is intended that [the Commissioner] shall take a high position in this matter and shall not claim for the Crown more than he sees the Crown is entitled to'.[145] He held that the Commissioner had refused to consider whether the assessment should be amended and in doing so had refused to perform his duty.[146] He also held that he would have arrived at the same conclusion if the Commissioner 'had exercised his power under s 97(1) capriciously'.[147]

138 The sentiment expressed by Isaacs J in Agricultural Service Engineers, and reinforced in Lighthouse Philatelics, that the Commissioner is obliged to collect the correct amount of tax, and only the correct amount of tax, is further reflected in Boyded.[148] There Hunt J held that the 'Commissioner, it is assumed, will do right both to the Crown and to the taxpayer'[149] with the consequence that if he allowed an objection it 'would be most improper for the Commissioner to continue to claim the tax identified in his original assessment following his decision to allow an objection, and it must ... be assumed that in all cases he will in fact amend his assessment to accord with his decision'.[150]

139 In our view, Hunt J's observation can be extrapolated to other circumstances in which it would be improper for the Commissioner to continue to claim the tax identified in an assessment, for example, where the Commissioner knows that amendments to assessments under s 19 are necessary to ensure the accurate assessment of land tax. We consider that it would be equally improper for the Commissioner to continue to claim to be entitled to an amount he knows to have been overpaid in response to an inaccurate assessment in the same way as it is improper for the Commissioner to continue to claim the tax identified in an original assessment following his decision to allow an objection. In our view, the nature of the power under s 19, and the pre-conditions that must be satisfied before it is enlivened, mean that once the Commissioner has knowledge that an assessment is inaccurate, and that an amended assessment is necessary to ensure the accurate assessment of land tax, then, in accordance with the Finance Facilities principle, the Commissioner has a duty to exercise his power under s 19.

140 We consider that the Commissioner here had knowledge that the assessments for the 1990-2002 land tax years were inaccurate and that an amendment was necessary to ensure their accuracy. This is discussed below.[151] In those circumstances, we consider that the Commissioner was under a duty to exercise his power under s 19 to amend.

141 Furthermore, it is clear that the Commissioner must have the power to do everything that is necessary and convenient for the achievement of the purpose of s 19. It is well understood that the grant of a power under statute includes with it 'every power and every control the denial of which would render the grant itself ineffective'.[152] In our view, the power to refund an overpaid amount is a necessary incident of the power to amend. Where the power under s 19 is exercised to reduce the amount of land tax for which a taxpayer is liable, it follows that the Commissioner must have an incidental power to refund. A power to refund must also bring with it what may be 'described as "an implied appropriation" out of consolidated revenue'.[153]

142 Indeed, here the Commissioner relied upon a power to refund upon the making of an amended assessment (and any necessary power of appropriation) when he issued amended assessments for the 2006 and 2007 land tax years and paid the refunds of $110,635 and $103,800 respectively.[154] He relied upon the same power when he indicated in the 23 March 2012 email that he would amend the assessments for the 2008-2011 land tax years and issue the refund of $300,238.75.[155] The Commissioner paid these refunds as an exercise of the power to amend assessments; that is, the refunds must have been paid as an incident of the power under s 19 to ensure that the assessments of tax for the 2006-2011 land tax years were complete and accurate. Those payments in themselves demonstrate that the power under s 19 must carry with it, as a necessary incident of the power, a power to refund which in turn necessarily entails an implied power of appropriation. Without it the power under s 19 would be rendered ineffective and, as mentioned, a statutory power ought not be construed in such a way as to render it ineffective.

143 It follows, in our view, that as the power of the Commissioner to amend an assessment under s 19 is, in the circumstances of the case, coupled with a duty to amend, then the Commissioner is also under a duty to refund and he has the necessary power of appropriation in order to do that. The power he has already exercised under s 19 with respect to the 2006-2011 land tax years ought then be exercised in precisely the same way in respect of the 1990-2002 land tax years.

(2) Did the Commissioner engage in conscious maladministration?

144 The Commissioner submits that by reason of the detailed objection and refund regimes, there is no warrant to imply into s 19 the independent powers and duties that ACN submits should be implied. He argues that to do so would circumvent the prescribed regimes. He contends that the judge was correct to hold that the objection and refund regimes are exclusive and exhaustive.[156]

145 Moreover, he submits that not only has he never expressly admitted that each of the 1990-2002 assessments is excessive but rather, his position has always been that the question whether the assessments are excessive cannot be agitated in these proceedings, brought outside the objection and refund regimes under the Act. As far as the Commissioner is concerned, 'the matter is closed'.[157]

146 He relies on the legislative history of the Act as irreconcilable with the notion that s 19 is directed at providing taxpayers with free-standing refund rights. In particular, he points to the fact that initially, until 1974, there was a three-year time limit on land tax refunds. In 1974 that time limit was removed.[158] In 1992 the time limit was reinstated and s 90A was inserted, the Treasurer explaining that taxpayers who had overpaid tax were entitled to a refund but 'there must be a point in time in which taxation matters are finalised'.[159] In 1993, following claims that the 1992 amendments were ineffective to bar refunds after three years, s 90AA was inserted, together with s 92A, clarifying that the Supreme Court's jurisdiction was intended to be limited by s 90AA, the Treasurer explaining that the purpose of the three-year limit on tax refunds was, as mentioned above, 'to provide certainty and finality to Victoria's revenue collections'.[160]

147 In particular, the Commissioner emphasises, as the judge accepted, that the 1992 and 1993 amendments were the expression of Parliament's will, in response to the decision of the Full Court of the Supreme Court of Victoria in Royal Insurance Australia Ltd v Comptroller of Stamps (Vic)[161] that s 20A, as it then stood, did not apply to proceedings for mandamus. Section 90AA(8) was inserted to ensure that the bar 'appl[ies] to proceedings which seek to use administrative law procedures to require things to be done which may result in a refund, as well as to proceedings which seek a refund directly'.[162] Inserted simultaneously with s 90AA(8) was s 20A(5) of the Limitations Act which was described in similar terms:

The Bill makes clear that section 20A applies to proceedings seeking administrative law remedies such as mandamus. This is necessary because of the recent decision of the Full Court of the Supreme Court of Victoria in Royal Insurance Australia Ltd v Comptroller of Stamps, which held that section 20A of the Act does not apply to mandamus proceedings.[163]

148 The Commissioner submits that the judge was correct to conclude that the objection and the refund regimes are the only means available to a taxpayer seeking to recover allegedly overpaid land tax. He argues that they are not merely optional remedies, where available, but, rather, are exhaustive and would be circumvented if taxpayers, having utilised neither procedure under the Act, were permitted to maintain mandamus proceedings seeking refunds under s 19.

149 To this, ACN responds by submitting that to reject the possibility of proceedings for mandamus being brought to recover overpayments is to ignore the fact that the Act expressly includes a means by which an overpayment may be established, in s 19. Section 19 is part of the statutory framework available to a taxpayer for recovery.

150 The difficulty for ACN is that s 19 not only confers on the Commissioner a power to amend but it also contains by its closing words the directive, as the judge observed,[164] that 'the validity of an assessment shall not be affected by reason only that any provisions of this Act have not been complied with'.[165] Those words reflect the terms of s 175 of the Income Tax Assessment Act 1936 (Cth) ('the ITAA')[166] which provide:

The validity of any assessment shall not be affected by reason that any of the provisions of this Act have not been complied with.

151 In Futuris[167] the High Court held that s 175 of the ITAA operates to protect an assessment from challenge by judicial review unless the assessment is provisional or interim or there has been conscious maladministration. A taxpayer is precluded from challenging the validity of an assessment by judicial review except on those grounds, although they may object in the manner set out in Part IVC of the ITAA.[168] Errors in assessment do not go to jurisdiction. The plurality said:

Section 175 must be read with ss 175A and s 177(1).[[169]] If that be done, the result is that the validity of an assessment is not affected by failure to comply with any provision of the Act, but a dissatisfied taxpayer may object to the assessment in the manner set out in Pt IVC of the Administration Act; in review or appeal proceedings under Pt IVC the amount and all the particulars of the assessment may be challenged by the taxpayer but with the burden of proof provided in ss 14ZZK and 14ZZO of the Administration Act. Where s 175 applies, errors in the process of assessment do not go to jurisdiction and so do not attract the remedy of a constitutional writ under s 75(v) of the Constitution or under s 39B of the Judiciary Act.[170]

152 This construction of s 175 of the ITAA has been consistently applied since.[171]

153 In Futuris, the Court expressly acknowledged that there is an exception where there has been a deliberate failure of due administration; the possibilities of such disregard 'point decisively against a construction of s 175 which would encompass deliberate failures to administer the law according to its terms'.[172] The plurality said:

Such failures manifest jurisdictional error and attract the jurisdiction to issue the constitutional writs. To the extent that there is any indication to the contrary in what was said by Mason and Wilson JJ in F J Bloemen Pty Ltd v Federal Commissioner of Taxation that should not be followed.[173]

154 ACN alleges that the Commissioner here engaged in conscious maladministration. As mentioned,[174] the judge rejected the allegation that the decision of the Commissioner to refuse to amend the assessments for the 1990-2002 land tax years evidenced a 'fundamental error' by the Commissioner. Her Honour did so primarily on the basis that she considered that the Commissioner was under no duty to exercise his power under s 19; that, having regard to the statutory scheme of the Act as a whole, the power under s 19 was a power to be exercised within the Commissioner's discretion.

155 In our view, the actual refusal of the Commissioner on 15 August 2013[175] to amend the assessments to make them accurate, in the circumstances of the case as we have described, amounted to conscious maladministration. The decision not to amend the 1990-2002 land tax assessments was deliberate. It was taken in the light of the knowledge of the duplication error and of the express admission made by the Commissioner that the duplication error had been committed with respect to the 2008-2011 land tax years. The context was one where the evidence was overwhelming that the duplication error was operative and enduring throughout the 1990-2002 land tax years.[176] The decision not to amend was taken after the Commissioner allowed objections based on the duplication error for the 2006 and 2007 land tax years, amended the assessments for those respective years by deleting the duplicate property, and provided a refund. By the time of the 15 August 2013 letter the then Treasurer had granted ex gratia relief for the 2003, 2004 and 2005 years in response to a request based upon the duplication error.

156 We consider that it would be untenable to suggest that at the time the Commissioner made the decision to refuse to amend he lacked the knowledge that in all probability the assessments for the 1990-2002 land tax years were based upon the duplication error and were inaccurate. As we have discussed, the s 19 power was thereby enlivened. There was no suggestion, as in the circumstances of Futuris,[177] that the duplication error, once the Commissioner became aware of it, would be remedied by a compensating adjustment determination. While it is not suggested that when the Commissioner issued the assessments for the 1990-2002 land tax years he acted otherwise than bona fide, it remains the case that his refusal to amend the assessments after having become aware of the duplication error, and in the knowledge that we take him then to have, meant that, at the time of his refusal on 15 August 2013, he was aware that the assessments did 'not reflect any rational assessment of the taxpayer's liability to tax'.[178]

157 In the 15 August 2013 letter the basis of the Commissioner's refusal to amend the assessments for accuracy was identified not as being that he had formed the view that the assessments were in fact accurate and required no correction but rather that the expiry of the limitation period for applying for a refund under the Act meant that the taxpayer would be precluded from being granted consequential relief regardless of the merits of the request for amendment. In effect, the Commissioner was relying upon the limitation provisions of the Act, as he saw them,[179] to preclude relief in the knowledge that the assessments for the 1990-2002 land tax years were based upon the duplication error and were thereby inaccurate. Yet the power conferred upon the Commissioner under s 19 is a power 'to ensure' the 'completeness and accuracy' of assessments. An amendment of the assessments for the 1990-2002 land tax years was necessary to ensure accurate assessments of land tax and the Commissioner must be taken to have known that. Importantly, as s 19 is, in terms, an 'own motion' power, the Commissioner had the power of his own motion both to amend assessments and to make the consequential payments. Relief was not dependent on any further step being taken by the taxpayer. Reliance on the limitation provisions of the Act was not to the point in those circumstances. In our view, the Commissioner's refusal to amend amounted to a deliberate disregard by the Commissioner of the scope of his powers without good reason or justification.

158 Indeed, we consider that in the circumstances of the case, the Commissioner's refusal to amend, as expressed in the letter of 15 August 2013, amounted to an implied admission that the duplication error occurred in each of the 1990-2002 land tax years, that the assessments for the 1990-2002 land tax years were thereby inaccurate, and that he wrongly collected taxes that were not otherwise due. Standing back and looking at the circumstances in the round there is an air of the Commissioner consciously refraining from stating his position on the accuracy of the assessments for the 1990-2002 land tax years. He has never expressly denied that the assessments for the 1990-2002 land tax years were inaccurate. He has not contended that those assessments are accurate. As mentioned,[180] the background to his letter of 15 August 2013 is significant, namely, that he had already expressly admitted the duplication error for the 2008-2011 land tax years and amended the 2006 and 2007 assessments by deleting the duplication error. He has never sought to explain how the assessments for the 1990-2002 land tax years are different from those for the 2006-2011 years and, as mentioned,[181] the evidence is compelling that the duplication error occurred in each of the land tax years 1990-2011. The Commissioner is aware of the fundamental principle that he is entitled to collect only that amount of tax for which a taxpayer is liable and no more, and he is aware of the power he has under s 19, yet the only explanation the Commissioner proffered for his refusal to amend in the 15 August 2013 letter is the unavailability of consequential relief 'whether or not each of the assessments were now amended as requested'.[182] The premise of the 15 August 2013 letter is that the duplication error was made for each of the 1990-2002 land tax years but ACN has no consequential entitlement to a refund because of the effect of a limitation period.

159 In our view, in the particular circumstances of this case,[183] the decision of the Commissioner not to amend the assessments constituted a deliberate failure of due administration. It amounted to a wilful refusal of the Commissioner to perform his duty without good reason or justification. In the language of Futuris, this 'manifest[s] jurisdictional error' and attracts the availability of judicial review.[184] Such a claim clearly falls outside of the objection and refund regimes.[185] We have already concluded that the power under s 19 was here enlivened, because the Commissioner had knowledge that the assessments for the 1990-2002 land tax years were inaccurate, and he had, therefore, a duty to exercise the power to amend to ensure the assessment was accurate.[186] We consider that the decision of the Commissioner not to amend the assessments when his power 'to amend an assessment ... to ensure its ... accuracy' was enlivened amounted to conscious maladministration for which mandamus is available. Subject to what is discussed below, and putting the question of interest to one side, the appropriate relief is an order compelling the Commissioner to exercise his power under s 19; that is, directing the Commissioner to issue amended land tax assessments to ACN for the 1990-2002 land tax years and an order directing the Commissioner to give effect to the amended assessments by refunding to ACN the excess amount.

160 With great respect to the judge, we consider that she erred in failing to view s 19 as an integral part of the statutory scheme which in the appropriate circumstances could give rise to a duty and failing to find that here there was conscious maladministration of the Act sufficient to found an action for mandamus to compel an exercise of the power under s 19.

161 There is some uncertainty as to whether the allegation by ACN of conscious maladministration extends to the constructive refusal by the Commissioner to amend the assessments in response to ACN's letter of 3 December 2012. ACN alleges that at that time the Commissioner appreciated that the duplication error had occurred and yet retained payments made by ACN to which he had no entitlement.[187] We do not consider that there is sufficient evidence with respect to the circumstances surrounding the failure of the Commissioner to amend the assessments in response to the 3 December 2012 request to draw the inference that there was conscious maladministration at that time.

162 On the view we have taken of the nature and scope of the power under s 19, and the circumstances of the case, the Commissioner was under a duty to amend ACN's assessments for the 1990-2002 land tax years and he has deliberately refused to do so. We consider that mandamus should issue to compel the Commissioner to perform his duty. In arriving at these conclusions we have not had recourse to the reasoning in Royal Insurance. We have not considered it necessary to do so. However, we proceed to identify the proposition for which Royal Insurance stands and then consider whether it has any implications for the circumstances here.

(3) What proposition does Royal Insurance stand for?

163 In Royal Insurance the taxpayer, Royal Insurance Australia Ltd ('Royal'), paid to the Commissioner of State Revenue amounts which it believed to be due under the Stamps Act as duty on premiums received in respect of workers' compensation policies issued by it. There were significant legislative changes to workers' compensation insurance between 1985 and 1987. Pursuant to the Accident Compensation Act 1985 ('the 1985 Act'), which came into operation on 1 September 1985, the Accident Compensation Commission became the sole insurer in respect of workers' compensation liabilities. An exemption was introduced with respect to premiums for workers' compensation insurance in respect of the issue, renewal or taking out of policies after 4:00pm on 30 June 1985. Further exemptions were introduced to cover 'cost-plus' policies by the Taxation Acts Amendment Act 1987 ('the 1987 Act'). Royal remained unaware of the amendments under the 1985 Act for some years and of the amendments under the 1987 Act for about two years. It continued to include in its monthly returns the amount of premiums that it received in respect of workers' compensation insurance policies issued or received after 30 June 1985 and paid stamp duty on those premiums. In 1989 Royal ceased to pay stamp duty on exempted premium income, because, it would appear, it received advice from the Commissioner. In 1990 Royal made a demand for repayment of the amount of stamp duty overpaid. The Commissioner did not agree to a refund with the result that Royal brought proceedings for recovery by way of originating motion.

164 As mentioned above, Royal's demand for a refund was governed by s 111(1) of the Stamps Act. For convenience, we set out the provision again:

Where the Comptroller finds in any case that duty has been over-paid, whether before or after the commencement of the Stamps Act 1978 he may refund to the company, person or firm of persons which or who paid the duty the amount of duty found to be overpaid.

165 Two days after the proceedings commenced, on 19 October 1990, the Commissioner found that duty had been overpaid but decided not to make a refund of any part of the amounts under s 111.

166 The Commissioner argued that the power under s 111(1) was permissive or facultative only, that being indicated by the use of the word 'may', especially by

166 comparison with the pre-amended text involving the mandatory 'shall ... refund'.[188] However, Mason CJ emphasised that the permissive words only created a presumption that the power conferred is facultative; '[n]or do they bear upon the question whether the discretion must be exercised in a particular way or upon a particular occasion'.[189] That question 'is to be solved from the context, from the particular provisions, or from the general scope and objects of the enactment conferring the power'.[190]

167 Mason CJ also emphasised that the construction of s 111(1) was to be approached on the basis that the Stamps Act conferred no authority for the retention of moneys other than in payment of stamp duty and that the power under s 111(1) to make a refund could not provide the necessary authority for retaining overpayments. He said:

In approaching that question [of the interpretation of s 111], the first and foremost consideration is that the Act is a taxing Act and that in terms it confers no authority upon the Commissioner to levy, demand or retain any moneys otherwise than in payment of duties and charges imposed by or pursuant to the Act. In that context, there is no persuasive reason why the grant of a positive discretionary power to make a refund, once an overpayment of duty has been found by the Commissioner to have taken place, should be treated as a source of authority in the Commissioner to retain the overpayment in the absence of circumstances disentitling the payer from recovery. Nothing short of very clear words is sufficient to achieve such a remarkable result. The Court should be extremely reluctant to adopt any construction of s 111 which would enable the Commissioner by an exercise of discretionary power to defeat a taxpayer's entitlement to recover an overpayment of duty. No reason emerges for thinking that the purpose of the provisions was other than to confer legal authority upon the Commissioner to refund an overpayment found by her to have taken place.

In Reg v Tower Hamlets London Borough Council; Ex parte Chetnik Developments Ltd, the House of Lords dealt with a discretionary power to refund in particular circumstances rates paid when not payable and not recoverable otherwise than by means of an exercise of the discretionary power. Lord Bridge of Harwich expressed the principle invoked by the House of Lords in these terms:

Parliament must have intended rating authorities to act in the same high principled way expected by the court of its own officers and not to retain rates paid under a mistake of law ... unless there were, as Parliament must have contemplated there might be in some cases, special circumstances in which a particular overpayment was made such as to justify retention of the whole or part of the amount overpaid.

Much the same comment may be made about s 111.[191]

168 On the other hand, Mason CJ also acknowledged that there might be a proper basis for resisting the making of a refund, especially if the Commissioner had changed his position adversely in reliance on the payments made or where a limitation period applied.[192] He went on to say:

At the same time, I cannot accept the proposition that, once overpayment has been found to have been made, the discretion must be exercised by making a refund. Assume the State has in good faith changed its position for the worse acting in reliance on the fact that the payment was made and received for duty apparently due and payable under the Act, the regime of monthly returns and payments being one of self-assessment, it could scarcely be suggested that a refusal to make a refund in such a situation could be an erroneous exercise of discretion. In David Securities Pty Ltd v Commonwealth Bank of Australia, it was recognized that, according to the principles of the law of restitution, such a change of position would constitute a good 'defence' to an action for recovery of money paid under a mistake of fact or law. It would be surprising, to say the least of it, if the conferral of a discretion to make a refund was intended to exclude power to refuse a refund when in the circumstances the taxpayer was not entitled to recover under the general law. An action which is time barred is another illustration of circumstances in which refusal to make a refund would be justified.[193]

169 However, absent relevant defences, he considered that the general common law principles of restitution applied in this context, namely, that a payer will be entitled to recover moneys paid in the mistaken belief that he or she was under a legal obligation to make the payments or that the payee had an entitlement to those payments, as recognised in David Securities Pty Ltd v Commonwealth Bank of Australia:[194]

As I have already indicated, the grant of the discretionary power to refund an overpayment should not be regarded as authority to refuse a refund which a taxpayer is entitled to recover according to the principles of the general law. It is necessary then to ascertain how Royal's claim to recover stands under the law of restitution. We begin with the proposition, accepted in David Securities, that mistake of law is no bar to recovery, and in this case there is no question but that Royal made the relevant payments in the mistaken belief that in law it was bound to do so. In one respect, Royal's belief at the time of payment was not mistaken: in the case of the cost-plus policies, payments were made when there was a legal liability to pay them. Only subsequently and retrospectively was an exemption granted. But the retrospective operation of s 2(4) of the 1987 Act enables one to say that, in the light of the law as it was enacted with retrospective effect in 1987, the payments of duty were made under a mistake as to the legal liability to pay them. In David Securities it was accepted that: 'the payer will be entitled prima facie to recover moneys paid under a mistake if it appears that the moneys were paid by the payer in the mistaken belief that he or she was under a legal obligation to pay the moneys or that the payee was legally entitled to payment of the moneys. Such a mistake would be causative of the payment.' And, prima facie, that is all that is required where, as here, the recipient has no legal entitlement to receive or retain the moneys. The recipient has been unjustly enriched.[195]

170 Mason CJ considered that, in refusing to make a refund, 'the discretion [in s 111] was exercised erroneously'[196] and that 'Royal was entitled to recover the overpayments in conformity with the law of restitution'.[197] More significantly for this aspect of the appeals, he held that:

(1) mandamus can be ordered to enforce a payment of money from the Crown;

(2) where there is a public duty to exercise a discretion, mandamus can be ordered to direct the exercise of the discretionary power;

(3) where a discretionary power can lawfully be exercised only in one way, mandamus can be ordered to compel the exercise of the discretion in the way in which it must be exercised.

171 In our view, it is apparent that Mason CJ took the existence of Royal's entitlement to the recovery of the overpayments in conformity with the law governing restitution as giving rise to the public duty on the Commissioner to exercise the discretion under s 111(1), and to exercise that power in a particular way. In other words, he considered that in the circumstances of the case, namely, the finding of an overpayment and the absence of any defence or limitation period, the discretionary power under s 111(1) gave rise to a duty to refund. In effect, the position adopted there by the Commissioner, namely to acknowledge the overpayment but to determine not to refund,[198] was found to be unlawful in the circumstances of the case.

172 Mason CJ concluded that, in the circumstances, it was appropriate that mandamus had been ordered to direct the Commissioner to refund the amount claimed:

The Appeal Division granted relief in the nature of mandamus by directing the Commissioner to refund the amount claimed. The Commissioner submitted that mandamus would not result in an order for payment of that money.

Although the argument was not elaborated, it is to be understood as invoking the principle that mandamus requires the exercise of the relevant statutory discretion rather than its exercise in a particular way. But that principle means no more than that the administrator to whom mandamus is directed will be required to perform the legal duty to the public which is imposed by the statute and ordinarily that duty is limited to exercising the statutory discretion according to law, there being no obligation to exercise the discretion in a particular way. However, if the administrator is required by the statute to act in a particular way and in certain circumstances, or if the exercise of a statutory discretion according to law in fact requires the administrator to decide in a particular way, so that in neither case does the administrator in fact have any discretion to exercise, then mandamus will also issue to command the administrator to act accordingly. Moreover, it has long been recognized that mandamus will issue as a remedy for certain forms of abuse of discretion upon the principle that 'the improper or capricious exercise of discretion is a failure to exercise the discretion which the law has required to be exercised'.

At one time it seems to have been thought that mandamus would not be granted to enforce payment of money by the Crown. However, in principle there can be no objection to the grant of relief by mandamus directed to a statutory officer requiring that officer to pay money if there be a public legal duty to so act. In the present case, the duty to exercise the discretion was a public duty and it was a discretion which, in the circumstances of this case, could be exercised only in one way. Consequently, mandamus will issue not only to compel exercise of the discretion according to law but also to compel it to be exercised in the way in which it must be exercised.[199]

173 Brennan J (with whom, as mentioned above,[200] Toohey and McHugh JJ agreed) directly addressed the submission made by Royal, namely, that 'the Commissioner is under a duty to refund overpaid duty once she "finds ... that duty has been over-paid"'.[201] As Royal contended, 'the condition governing the existence of the power to refund - a finding of overpayment - specifies the circumstances in which the power must be exercised'.[202] Brennan J contrasted the wording of s 111(1) with its predecessor,[203] which had used the mandatory 'shall', clearly imposing a duty to refund but one that 'could arise only if the party entitled applied for a refund within twelve months after the overpayment had been made'.[204] He considered that Royal's submission would be surprising as it would create a duty to refund, despite the weakening in the language from the mandatory 'shall' to the facilitative 'may', even if no application had been made and there had been delay. As he said:

If Royal's submission be correct, the new s 111(1) imposed on the Comptroller a duty to refund any overpayment, whether or not there was a legal liability to refund and irrespective of delay in discovery of the overpayment or in the making of a demand for a refund. That would be a surprising construction to place on s 111(1).[205]

174 Brennan J went on to consider that for a duty to arise under s 111(1) there must be an antecedent legal liability to refund. In examining the legislative history he pointed to the introduction of an express appropriation power under s 166D that was cast in terms of providing a standing appropriation for the amounts that 'the Comptroller of Stamps becomes liable to pay ... in accordance with the provisions of this Act'.[206] He then said:

The Commissioner's liability to pay must be the source of her duty to refund. That liability cannot arise simply from her finding that an overpayment has been made. Some overpayments might be made without the Commissioner's incurring of any liability to refund - for example, duty paid in compromise of the Commissioner's claim when it is subsequently discovered that the compromise amount was, or included, an overpayment of duty. The Commissioner's liability must arise aliunde, either under statutory provisions other than s 111(1) or under the general law.[207]

175 He thus clearly rejected the proposition that a finding by the Commissioner of an overpayment in itself gives rise to a duty to refund; rather, a liability to pay must arise 'aliunde' (that is, from another place),[208] from some other section of the Stamps Act or under the general law. It may be argued that Brennan J's requirement that there be a separate liability to pay only arose because of the statutory language of s 166D and its reference to the Commissioner becoming 'liable to pay'. Brennan J did acknowledge that before the introduction of the express power of appropriation in s 166D (that is, before the introduction of a reference to the Commissioner's liability) it was arguable that the Commissioner had the power to refund. However, he limited the scope of that implied power to refunds made ex gratia. It would seem that he accepted that for an obligation to refund to arise from a discretionary power there was a requirement for a separate liability.

In terms, s 111(1) confers a discretionary power on the Commissioner to refund moneys overpaid out of the Consolidated Fund of Victoria (in lieu of applying to the Treasurer for the money), but creates no duty to do so. In other words, once the Commissioner finds that an overpayment has occurred, there arises a power to make a refund by withdrawing from the Consolidated Fund an amount which is limited to the amount found to have been overpaid but which, by reason of s 166D, does not exceed the amount which the Commissioner is liable to pay. But no enforceable obligation to make the refund arises merely from a finding that there has been an overpayment. It is arguable that, prior to the commencement of s 166D, the Commissioner was empowered in exercise of her discretion to refund an overpaid amount ex gratia where there was no legal liability to refund. Presumably, s 111(1) would have been construed as an implied appropriation. But the express appropriation of the Consolidated Fund by s 166D is limited to refunds in discharge of liabilities of the Commissioner. If the Commissioner is liable to make a refund she is liable 'to pay amounts in accordance with the provisions of this Act', that is, she is liable to discharge her liabilities in accordance with s 111(1). But she is under no duty to make a refund unless there be an antecedent liability to do so. Unless such a liability exists, there is no duty to exercise the power conferred by s 111(1) nor any authority to do so.[209]

177 He accepted that if there was a liability to refund, then 'an exercise of the power conferred by s 111(1) ... is the means by which the Commissioner's legal liability is discharged'[210] and a refusal to do so would be reviewable in accordance with the Julius principle referred to above[211] where the circumstances 'couple the power with a duty'.[212] Much like Mason CJ, he accepted that where the circumstances require that a discretionary power be exercised in only one way, the duty created is enforceable by mandamus. As Brennan J put it, there is then 'no residual discretion' to refuse to make a refund. He said:

The Commissioner is a public officer vested with a power to be exercised for the purpose, inter alia, of discharging her liabilities. When the power exists and the circumstances call for the fulfilment of a purpose for which the power is conferred, but the repository of the power declines to exercise the power, mandamus is the appropriate remedy even though the repository has an unfettered discretion in other circumstances to exercise or to refrain from exercising the power. Mandamus will go where there is a duty to pay money. In this case, there is no residual discretion in the Commissioner to refrain from making a refund in exercise of her powers under s 111(1) once she finds that there has been an overpayment and there is a legal liability to refund the amount found to have been overpaid.[213]

178 He thus accepted the analysis, based upon the Julius principle and Finance Facilities, that in certain circumstances, the discretionary power under s 111(1) could give rise to a duty to refund. But under what circumstances would it give rise to such a duty? For Mason CJ, the existence of Royal's entitlement to the recovery of the overpayments in conformity with the law of restitution, and the absence of any defence or limitation period, gave rise to the public duty on the Commissioner to exercise the discretion under s 111(1), and to exercise that power in a particular way by giving a refund.[214] For Brennan J, the finding of an overpayment together with the legal liability to refund gave rise to an enforceable duty upon the Commissioner to exercise the power under s 111(1). The critical question is: for Brennan J, what was the source of the antecedent legal liability to refund? In the circumstances of the case Brennan J, like Mason CJ, recognised the Commissioner's legal liability to refund as arising from the entitlement by Royal to the recovery of overpayments in conformity with the law of restitution. This is apparent from the following passage:

Some of the moneys overpaid by Royal were paid under a mistake. [Some] amounts ... were paid under a mistake as to [the] existence of a statutory liability to pay; [an] amount ... was paid under a mistake as to the quantum of premiums to be received or, alternatively, was paid provisionally pending final determination of the quantum of the premiums actually received. In the case of [certain] amounts ... the Comptroller must be taken to have known at all material times that the statutory liability had been repealed and that she had no entitlement to retain these amounts. It would therefore be unjust that the Commissioner should retain these amounts; they were recoverable under the general law of restitution. As [another] amount ... was paid on the understanding that the amount paid would be adjusted when the quantum of the premiums on which the payments of stamp duty had been calculated became known, the Comptroller was bound to refund or to allow credit for the amount of the overpayment when ascertained.[215]

179 With respect to the payment specifically affected by the 1987 Act he held that 'the Commissioner is retrospectively disentitled to retain'[216] it, but treated the liability to refund as a statutory liability, in consequence of the 1987 Act, rather than a liability at common law.

180 The judge here characterised the payments made by ACN as of the same nature as those made under the 1987 Act but, significantly, without any retrospective removal of authority.[217] As mentioned above,[218] the judge rejected the view that there was an operative mistake. It was because of that finding (which we consider to be erroneous)[219] that she aligned the payments made by ACN with those made in Royal Insurance under the 1987 Act. In the absence of an operative mistake, she rejected the view that the statutory power to amend assessments under s 19 gave rise, in the circumstances of the case, to a duty to refund. This was not so much an instance of her Honour misapplying Royal Insurance, as ACN submits, but of her distinguishing it.

181 Brennan J concluded that the 'windfall gain' defence had no application and nor did the then s 20A of the Limitations Act.[220] If any limitation period applied it would have been the six year period prescribed under s 5(1) of the Limitations Act and the proceedings had been commenced within that period.[221] He noted that, as the proceedings had been brought for relief in the nature of mandamus, any limitation period would apply only by analogy:

Of course, the application made by Royal is not an action for the recovery of money; it is for relief in the nature of mandamus. The relevance of the limitation periods is that they mark the periods during which a legal liability to refund would have been enforceable by action, if s 111(1) had not transformed the cause of action into a right to performance by the Commissioner of her duty to exercise her power to refund. In the exercise of the Court's jurisdiction to grant mandamus to compel the Commissioner to discharge her duty by making refunds under s 111(1), the Court should apply the six-year period of limitation, refusing relief when proceedings are not brought within that period. Here, the proceedings were brought within time and an order compelling the Commissioner to make the relief claimed was rightly made.[222]

182 The relevant proposition for which Royal Insurance stands as authority is that the power conferred upon the Commissioner to make refunds in the event of overpayments under s 111(1) gave rise to a duty to refund, enforceable by mandamus, where the Commissioner would have been liable, under the general law of restitution, to repay payments made under a mistake. For the power under s 111(1) to be enlivened, it was necessary to establish, relevantly, that the overpayments would be recoverable in restitution, that is, that the overpayments were made under a mistake, and that no limitation period would bar recovery. The statutory power 'transformed the cause of action [in restitution] into a right to performance by the Commissioner of her duty to exercise her power to refund'.[223]

183 We distinguish between the nature of the power with which Royal Insurance was concerned and the nature of the power under s 19. We consider that they are very different powers, in that the power under s 19 is a power 'to ensure' the accuracy of assessments, and a power that can be exercised on the Commissioner's own motion. Both powers depend upon the Commissioner having knowledge of the irregularity; s 111(1) depending upon the Commissioner finding that duty had been over-paid and s 19 depending upon the Commissioner thinking it necessary to amend an assessment to ensure completeness and accuracy.[224] We have already concluded that the nature of the power under s 19, in the context of the circumstances we have described, gives rise to a duty upon the Commissioner to amend ACN's assessments for the 1990-2002 land tax years and to refund the excess amount.[225] Given the particular nature of the power under s 19, we consider that the duty to amend may not require a separate and antecedent liability upon the Commissioner to amend the assessments based upon ACN establishing an underlying claim in restitution. We consider this question to be open. However, if we are wrong about this, we turn to consider whether, in the circumstances of the case, ACN's claim at common law in restitution would be made out.

184 A claim in restitution for money paid under a mistake depends crucially upon characterising the nature of the mistake made. We turn to consider what was the nature of the mistake alleged here.

(4) What was the character of the alleged mistake?

185 The judge below repeatedly characterised the alleged mistake under which ACN made the relevant payments during the 1990-2002 land tax years as an alleged mistake on behalf of ACN as to its legal liability to pay land tax during those years. Her Honour relied upon the manner in which ACN had pleaded its case, emphasising that it had claimed that payment had been made 'in the mistaken belief that the land tax liability as assessed by the defendant in the assessments for the 1990-2002 years was properly due and payable to the defendant under the LTA 1958, and that it was legally obliged to make those payments'.[226] As mentioned, the judge rejected the submission that the belief was relevantly mistaken because she took the view that ACN did have a legal liability to pay whatever amount was assessed and that its payment of $363,680[227] was made in exchange for the good consideration of the discharge of a statutory debt.

186 We consider that the judge was wrong in the characterisation she gave to the alleged mistake under which ACN made its payments. She was not bound to describe the mistake in precisely the terms ACN had adopted in its pleadings, especially when the evidence revealed that the duplication error had been made. While the Commissioner only admitted the duplication error with respect to a limited number of years (2008-2011) it was the same duplication error that was alleged by ACN to have been committed during the entire period of 1990-2011 and relevantly the 1990-2002 land tax years. In our view, before examining whether there was an operative mistake it was necessary for the judge to characterise the alleged mistake under which the payments were made to reflect the allegation made by ACN that the Commissioner had committed a duplication error with respect to ACN's landholdings for the 1990-2002 land tax years. As mentioned above,[228] the mistaken belief which caused ACN to make the payments it did was, as Davis said in his evidence, a belief on behalf of ACN not only 'that it was legally obliged to make these payments' but also, and importantly, the belief 'that the landholdings listed for the plaintiff in the assessments issued by the defendant [the Commissioner] for these years were accurate'.[229]

187 ACN relied on the Commissioner to have accurately identified ACN's landholdings for the purpose of issuing the assessments he did. It made its payments in the belief that the assessments were accurate in that they accurately identified ACN's landholdings, which they did not. The duplication error rendered the assessments inaccurate; it thus rendered the belief under which ACN made the payments it did a mistaken belief. With respect, her Honour was wrong to characterise the mistaken belief without reference to ACN's belief in the accuracy of the landholdings identified by the Commissioner in his assessments. In other words, the judge was wrong to characterise the alleged mistake of the taxpayer without reference to the duplication error. Had her Honour characterised the belief by reference to ACN's understanding of the accuracy of the assessments she may have acknowledged the significance both of the Commissioner's duplication error and of the question whether the duplication error occurred throughout the 1990-2002 land tax years. The judge characterised the belief under which ACN made the payments it did without reference to the duplication error as though that error bore no relevance to the question of whether ACN's belief was mistaken. We consider that the duplication error is of central significance to a proper characterisation of the belief under which ACN made the payments it did, and that this linkage is apparent from the evidence of Davis. We consider that the judge was wrong to characterise ACN's belief in a manner that did not reflect that linkage.

188 In our view, the judge's mischaracterisation of the belief under which ACN made its payments led her erroneously to reject ACN's submission that an operative mistake had occurred. It also led her to reason, wrongly, that ACN received good consideration for the payments it made.[230]

189 We have already found that the Commissioner's duplication error persisted, relevantly, throughout 1990-2002.[231] We thus consider that the judge ought to have concluded that the payments ACN made during that period were paid under the mistaken belief that there was a legal liability to make those payments on the basis that the assessments for those years accurately identified ACN's landholdings.[232] The mistake was operative and enduring.

(5) Would an underlying restitution claim be made out?

190 We have concluded that here there was an operative mistake on behalf of ACN relevantly when it made the payments for the 1990-2002 land tax years.[233]

191 No liability for land tax in fact existed in respect of '65 Albany Road' as a duplicated landholding, for the simple reason that this landholding was already included within the square metres of land assessed for land tax in respect of '2 Ottawa Road'.

192 ACN submits that the Commissioner is enriched by the payments made in respect of '65 Albany Road', not being entitled to the excess amount, and that its retention of the excess amount in the knowledge that it is not entitled to it is unjust. It submits that its claim for money had and received is therefore made out, having established a causative mistake of law resulting in the enrichment of the Commissioner at ACN's expense. It claims it would be entitled to restitutionary relief under the general law.

Restitutionary relief, as it has developed to this point in our law, does not seek to provide compensation for loss. Instead, it operates to restore to the plaintiff what has been transferred from the plaintiff to the defendant whereby the defendant has been unjustly enriched. As in the action for money had and received, the defendant comes under an obligation to account to the plaintiff for money which the defendant has received for the use of the plaintiff. The subtraction from the plaintiff's wealth enables one to say that the defendant's unjust enrichment has been 'at the expense of the plaintiff'.[234]

194 The Commissioner responds by reiterating that ACN paid the land tax assessments for the 1990-2002 land tax years inclusive in good faith and in the belief that each land tax assessment issued by the Commissioner constituted a proper and lawful demand for the payment of all the tax assessed. He argues that the belief held by ACN, and specifically by Davis, was not mistaken, but correct, as a statutory 'tax debt' was created by each assessment, excessive or not. Each payment, of the exact amount assessed, discharged a legal obligation to pay. A payment made in discharge of a legal obligation to pay cannot be recovered under the law of restitution.

195 For the reasons we have given above, we consider that the belief held by ACN was not correct but was indeed mistaken.[235] In particular, the excess amount was paid by ACN under a mistaken belief that there was a legal liability to make those payments on the basis that the assessments for those years accurately identified ACN's landholding. In our view, the Commissioner's duplication error throughout the 1990-2002 land tax years deprived the Commissioner of the lawful authority to demand or retain the excess amount. In the absence of any statutory authority, it is unjust that the Commissioner is enriched at ACN's expense by his retention of the excess amount when aware of the duplication error throughout the 1990-2002 land tax years. These matters are sufficient to give rise to a prima facie obligation on the Commissioner to make restitution on a claim for money had and received in respect of payments made under a mistake. This was not displaced by circumstances that would render an order for restitution unjust.[236] As the High Court said in David Securities:

If the payer would not have paid the money had the payer known all the relevant circumstances, both legal and factual, the defendant is unjustly enriched by the receipt.[237]

196 It is clear that the power to amend under s 19 gives the Commissioner no authority to retain payments without authority, just as it was recognised in Royal Insurance by Mason CJ that s 111(1) provided no such authority.[238] Moreover, as we explain below,[239] the Commissioner's duplication error deprived the payments of the character of 'a sum payable for tax' within the meaning of s 39 of the Act. No reliance can be placed on the conclusive evidence provision under s 20 of the Act in this context because the Commissioner produced no assessments for the 1990-2002 land tax years. In any event, it is not the issuing of assessments (under s 17) which gives rise to a statutory debt; it is s 39, which we consider not to apply here. This observation also explains why the judge's attempt to distinguish Royal Insurance on the basis that in that case there were no assessments issued by the Commissioner[240] was unfounded.

197 The fact that the excess amount was paid cannot convert it into 'a sum payable for tax' within the meaning of s 39 of the Act[241] especially when the excess amount was paid under the mistaken belief we have identified. The payment of the excess amount was never a 'tax' payment given that the Commissioner never had the authority to demand it under the Act, the demand being based upon the duplication error.[242] In the words of Mason CJ, the Act 'is a taxing Act and that in terms it confers no authority upon the Commissioner to levy, demand or retain any moneys otherwise than in payment of duties and charges imposed by or pursuant to the Act'.[243] Furthermore, as mentioned,[244] the Act does not generate a statutory debt from the issuing of an assessment; the debt depends upon the payment being properly characterised as 'a sum payable for tax'. The Commissioner having no authority under the Act to demand the excess amount, it was never 'land tax' properly so-called within s 57 of the Act.

198 For these reasons, we consider that the Commissioner's claim to have a 'defence' to ACN's claim in restitution based upon the good consideration he gave by way of the discharge of a statutory debt should be rejected.

199 We consider that, in the circumstances of the case, the common law would impose a legal obligation to provide restitutionary relief (subject to the application of any relevant limitation period).

200 This establishes a separate and antecedent liability at common law against the Commissioner for restitution were it necessary for there to be such an antecedent liability. (Our primary position is that there may be no such need.)[245] The separate liability provides an alternative ground by which to convert the word 'may' in s 19 from that of an empowering or facilitative word to a word which, in the circumstances of the case, has mandatory force, in accordance with the observations of Brennan J in Royal Insurance. The duty is enforceable by mandamus, most especially because here, as we emphasised above,[246] the Commissioner has refused to perform his duty without good reason or justification. In accordance with the ratio of Royal Insurance, the statutory power in s 19 'transformed the cause of action [in restitution] into a right to performance by the Commissioner of [his] duty to exercise [his] power'[247] relevantly to amend the assessments for the 1990-2002 land tax years and to give effect to the amended assessments by refunding the excess amount.

201 However, as the judge noted,[248] Lehane J in Chippendale Printing Co Pty Ltd v Commissioner of Taxation[249] took the view that the effect of Brennan J's judgment in Royal Insurance was that the transformation of a common law action in restitution into a statutory right to the performance by the Commissioner of a statutory duty leaves the taxpayer with only one recourse, namely, the proceeding for mandamus. He said, referring to Royal Insurance:

In the proceedings orders were sought compelling the Commissioner to exercise her discretion in favour of Royal Insurance, which had overpaid duty. Common law relief was not sought. The effect of the judgment of Brennan J, with whom Toohey and McHugh JJ agreed and whose judgment therefore represents the views of the majority of the Court, is that the Commissioner could be compelled to exercise her power under the section in circumstances where the general law would create a duty to refund the overpaid amount (at 88) but that (at 92) the section had 'transformed the cause of action into a right to performance by the Commissioner of her duty to exercise her power to refund'. In other words, though the circumstances (and the only circumstances) in which the Commissioner might (and should) exercise her discretion under the section were those where the common law would impose a legal obligation to make a refund, the claimant's only recourse was an action to compel the appropriate exercise of the discretion, not an action against the Commissioner (or the Crown) to recover the overpaid duty at common law.[250]

202 This is supported also by the observation of Brennan J, quoted above,[251] that 'an exercise of the power [to refund] is the means by which the Commissioner's [antecedent] legal liability is discharged'.[252]

203 As we explained above,[253] the significance of the claim in restitution in Royal Insurance was that it satisfied the requirement identified by Brennan J in that case that there be a separate and antecedent liability on the Commissioner to refund the overpayments, namely, with respect to the bulk of the payments,[254] a liability that the common law would impose to provide restitution. As Lehane J observed in Chippendale Printing, common law relief was not sought in Royal Insurance. Nor was it ordered. The relief in Royal Insurance consisted in an order in the form of mandamus directing the Commissioner to refund the amount in question. The orders were made by the Full Court of the Supreme Court[255] and the High Court dismissed the appeal.[256]

204 ACN relies on Royal Insurance as its principal authority in its restitution proceeding for the proposition that a claim for money had and received lies against the Commissioner from which restitutionary relief will flow. However, the High Court in Royal Insurance upheld the taxpayer's claim in restitution only insofar as it demonstrated that the requirement for an antecedent liability was satisfied. It did not uphold a claim in restitution as a distinct cause of action for which it granted relief. Indeed, as mentioned, the claim in restitution was not relied upon as a distinct cause of action and nor was restitutionary relief sought. ACN did not point to any other Australian authority where restitutionary relief had been sought and granted against the Commissioner or equivalent statutory office-holder within the context of a statutory scheme similar to the Act.

205 We consider that ACN has successfully demonstrated that here, if necessary, the claim in restitution is made out in the sense that the requirement for an antecedent liability on behalf of the Commissioner has been established. In other words, we consider that the circumstances are ones where, in the words of Lehane J in Chippendale Printing, 'the common law would impose a legal obligation to make a refund'[257] by reason of the excess amount having been paid under a mistake. We consider that this would be sufficient, if necessary, to transform the power under s 19 into a statutory duty on the Commissioner to amend ACN's assessments for the 1990-2002 land tax years and to give effect to the amendments by repaying the excess amount.

206 In the circumstances we consider it unnecessary to resolve the Chippendale Printing question as to whether the only recourse available to ACN was to bring a proceeding for mandamus to compel the appropriate exercise of discretion and that the action to recover in restitution was not independently available to it.[258] Here, ACN did bring proceedings for mandamus and that proceeding has transformed its common law cause of action for restitution into a statutory right to the performance of a duty on the Commissioner. We consider that reliance on Royal Insurance can support no greater proposition.

207 We turn then to the issue of limitation periods.

(6) Which limitation period applies - s 90AA, s 20A or s 5(1)?

208 The primary submission of ACN is that the duty of the Commissioner, in the circumstances of the case, to make amended assessments for the 1990-2002 land tax years and to act on those amendments by refunding the wrongly demanded sum, is not governed by any limitation period.[259] It submits that a proceeding for mandamus, or for restitution, may be brought without the need for compliance with any limitation period. It emphasises that the terms of s 19 expressly provide for the power to be exercised 'from time to time' and thus at any time.

209 We noted above[260] that s 19 is cast in terms of an 'own motion' power and that relief is not dependent on any further step being taken by the taxpayer. When exercised by the Commissioner as an own motion power we consider there would appear to be no temporal restriction on its exercise. However, ACN relies on its right to enforce the performance of the Commissioner's duty to amend the 1990-2002 assessments, and to refund, arising under s 19 in the circumstances of the case. That is, it relies not on the own motion aspect of s 19 but on its capacity to enforce the performance of the power under s 19 by mandamus.

210 The question arises whether any limitation period under the Act, or under the Limitations Act, applies to govern such a proceeding.

211 The Commissioner primarily relies on s 90AA(1) of the Act as a bar to the proceeding and, alternatively, relies on s 20A(1) and/or s 5(1) of the Limitations Act.

212 It is clear that a proceeding for mandamus is included within the proceedings sought to be governed by the limitation period under s 90AA.[261] ACN submits that, nevertheless, s 90AA does not apply because the proceedings are not 'for the refund or recovery of tax paid under, or purportedly paid under, this Act'. In short, the submission is that because the operative mistake ultimately deprived the Commissioner of authority to take, and retain, the excess amount, the excess amount could not be aptly described as a payment made 'under, or purportedly paid under' the Act. ACN relies on observations made in Royal Insurance to the effect that payments made under a mistake of law as to the authority of the Commissioner to demand payments were not amounts either paid under the Act or under the purported authority of the Act. These observations were made in the context of the then s 20A[262] but ACN focuses on what is substantially similar language in s 90AA. In particular, Mason CJ noted that it 'is not possible to read the words "under the authority or purported authority" as denoting "under a mistaken belief as to authority"'.[263]

214 If we are correct in concluding that the proceeding for mandamus does not require for its success that ACN establish an antecedent liability at common law in restitution then we consider that the relevant limitation period is the six years under s 5(1)(d) applicable to '[a]ctions to recover any sum recoverable by virtue of an enactment'.[264] The proceeding for mandamus, being a proceeding to compel the performance of a statutory duty, is a proceeding to recover a sum recoverable by virtue of an enactment.

215 If we are wrong, however, and there is a need for ACN to establish an underlying claim for restitutionary relief, then we consider that s 20A(1) applies.

216 Section 20A(1) of the Limitations Act[265] exactly addresses the claim that the proceedings are for 'the recovery of money paid ... under a mistake (either of law or fact)' and that the payments were 'by way of an amount that is attributable to ... purported tax'. Section 20A(1) is clearly intended to apply to mistake-based restitutionary claims. This is reinforced by its legislative history, being introduced to extend to payments made under a mistake after the Full Court of the Supreme Court in Royal Insurance Australia Ltd v Comptroller of Stamps (Vic)[266] gave a confined meaning to the then s 20A.[267] As mentioned,[268] Mason CJ observed in Royal Insurance that mistake-based restitutionary claims did not meet the description of proceedings for the recovery of 'tax ... paid under the authority or purported authority of any Act', the relevant terms in which s 20A had been cast,[269] and substantially similar to the terms of s 90AA.[270]

217 We consider that the payment of the excess amount for the 1990-2002 land tax years, being paid in response to assessments issued by the Commissioner under the Act, in respect of ACN's landholdings for each land tax year, albeit inaccurately identified, is aptly described by the current language of s 20A(1). In our view, the excess amount was paid 'by way of an amount that is attributable to ... purported tax under a mistake (either of law or fact)'.[271] While in truth the excess amount was not lawfully demanded as land tax, it nevertheless had the character of an amount that is 'attributable to ... [a] purported tax' payment. Even if a payment made under a mistake of law is not 'tax ... paid under the authority or purported authority of any Act', as Mason CJ observed, we consider it may nevertheless be 'an amount ... attributable to ... purported tax'.

218 We consider, with respect, that the judge was wrong to conclude that s 20A of the Limitations Act was excluded by s 90AA of the Act, or not enlivened here, because the proceeding was not brought after an application had been made for a refund under s 90AA(2).[272] We have already concluded that, in the circumstances, it was not necessary for ACN to have made an application for a refund given that we consider its mandamus proceeding to be properly founded on its allegation of conscious maladministration. We consider that s 20A(1) applies because it is the later[273] and more specific statutory provision; it impliedly repeals s 90AA or restricts its scope of operation in certain limited circumstances, relevantly, where the proceedings are for the recovery of money paid under a mistake of law or fact.[274] We consider that the same limitation provision that applies to a proceeding for restitutionary relief, s 20A(1), applies by analogy to the mandamus proceeding.[275]

219 Moreover, we consider that if s 20A applies, the applicable limitation period is s 20A(1)(a), namely, a period within 12 months after the date of payment.

220 We do not consider that s 20A(1)(b) applies. On this alternative, s 90AA continues to have a role to play because the proceeding is brought 'in accordance with another Act that provides for the refund or recovery of the money', and the longer period of three years and six months prescribed under s 90AA would apply. ACN urged the application of s 20A(1)(b) on the basis that the two provisions, s 90AA and s 20A(1), should be accommodated by construing them harmoniously in accordance with the principle that where 'two statutes ... share a field of operation' they 'should be construed in a way which best achieves a harmonious result'.[276] This is not to suggest that s 20A(1)(b) is specifically aimed at s 90AA; rather, s 20A(1)(b), where it applies, picks up various limitation provisions in State legislation concerned with the recovery of tax and thereby permits the beneficial operation of the extension provisions such as s 27 to enlarge those limitation periods.

221 However, with respect to s 90AA, the difficulty in suggesting that s 20A(1)(b) indirectly picks up the limitation period in s 90AA lies in s 90AA(4). For convenience we set it out again:

(4) Sub-section (3) applies whether or not the period for bringing proceedings for the refund or recovery of the amount prescribed by section 20A(1) of the Limitation of Actions Act 1958 has expired.

222 Section 90AA(3) is premised upon a person having lodged an application for a refund within three years after the payment was made, in accordance with s 90AA(2). The person is then entitled to bring proceedings for the recovery of the amount if the Commissioner has, within three months after the application was lodged, refused to make a refund or failed to refund the amount.[277] The proceedings are to be brought within a further three months from the date of the refusal, or after the expiration of the three month period during which the Commissioner has failed to refund or apply the amount, whichever first occurs. While sub-s (2) of s 90AA dictates the manner of the application for a refund and the timing of the application, it is sub-s (3) of s 90AA which governs the bringing of proceedings and the timing of the commencement of proceedings.

223 Section 90AA(4) expressly regulates the relationship between s 20A and s 90AA so that a person who applied for a refund within three years[278] is permitted to being proceedings within the six month period provided for under s 90AA(3), whether or not the period under s 20A(1) of the Limitations Act has expired. In our view, the 'period for bringing proceedings for the refund or recovery of the amount prescribed by section 20A(1)', referred to in s 90AA(4), must be referring to the 12month period in s 20A(1)(a). In other words, s 90AA(4) expressly permits proceedings to be brought for the refund or recovery of tax paid under, or purportedly under, the Act whether or not the 12-month period prescribed under s 20A(1) of the Limitations Act has expired. If s 90AA(4) referred to the longer period allowed for under s 20A(1)(b), that longer period would be the three years and six months permitted by s 90AA(3). This would mean that in effect s 90AA(4) would be saying that proceedings are permitted to be brought under s 90AA(3) (namely, a period of three years and six months) whether or not the period for bringing proceedings prescribed by s 20A(1)(b) of the Limitations Act (namely, a period of three years and six months) has expired. But this would make little sense.

224 A more sensible construction of s 90AA(4) would suggest that its role is to reinforce the permissibility of proceedings being brought against the Commissioner for refunds or recovery beyond the short 12-month period allowed for under the Limitations Act, provided that the proceedings are brought in accordance with the requirements of s 90AA.

225 In any event, for the reasons we have given, we do not consider that the circumstances here amount to 'a proceeding in accordance with another Act', within the terms of s 20A(1)(b), because we do not consider that the proceedings meet the description under s 90AA of being 'proceedings for the refund or recovery of tax paid under, or purportedly paid under, this Act'.[279]

226 It is unnecessary to resolve this issue. It was common ground that neither of ACN's proceedings was brought within time, either within the six year limitation period prescribed by s 5(1)(d), the 12 month period prescribed by s 20A(1)(a), or the extended period prescribed by s 90AA if applicable under s 20A(1)(b).

(7) Is the limitation period postponed under s 27?

227 ACN submits that s 27 applies to postpone the limitation period and that its effect would be that the limitation period did not commence to run until 23 March 2012 when ACN became informed of the Commissioner's duplication error for the 2008-2011 land tax years.[280] The proceedings were brought within 12 months following the commencement of the postponed limitation period.[281] This would satisfy the six year limitation period under s 5(1)(d) and the 12 month limitation period under s 20A(1)(a).

228 Section 27 applies only in respect of 'any action for which a period of limitation is prescribed by this Act'.[282] It is clear that the limitation period of six years under s 5(1)(d) and that of 12 months under s 20A(1)(a) are limitation periods 'prescribed by this Act'.

229 In response, the Commissioner submits that s 90AA(1) applies and extinguishes any action; it does not merely bar a remedy. We have already concluded that we do not accept that s 90AA(1) applies here.

230 The Commissioner further relies on his contention that there was in truth no mistaken payment and therefore no limitation period prescribed by s 20A, for s 27 to extend. He also relies on this contention to submit that the requirement under s 27(c), namely, that the 'action is for relief from the consequences of a mistake' is not made out.[283] We have already rejected the contention that there was no mistake under which the payments were made.

231 The Commissioner submits that, even assuming s 27 could otherwise apply, the judge did not err in finding that ACN had not proven that it 'could [not] with reasonable diligence have discovered' the error in the 1990-2002 assessments before 2012. He emphasises that ACN carries the onus of proof in demonstrating that the limitation period should be postponed. He also submits that the judge was correct in identifying that there was no evidence as to what took place when ACN became the owner of the two properties in 1988; no evidence as to what information was forwarded to the Commissioner; and no evidence as to relevant rate notices from the City of Stonnington. The Commissioner takes by way of example, the 2002 land tax year. He submits that if ACN had paid local rates on $2,010,000 worth of land (as would be indicated by Table 2)[284] and then received a land tax assessment assessing both land of that value ($2,010,000) and supposed additional land of $1,830,000,[285] then it ought to have suspected that something was amiss; at the least it 'could with reasonable diligence have discovered' the alleged duplication error.

232 ACN submits that the mistake was not discovered until 23 March 2012, and was not capable of being discovered with reasonable diligence before the making of the admission by the Commissioner on that date. The error is not discernible from the assessments issued by the Commissioner; they refer to the two properties with separate land ID references and they neither explained the landholdings in issue, nor how land tax was calculated by reference to those landholdings. The differential between the site values of the landholdings roughly equated to the difference in size of the two properties and the ratio remained constant.[286] The relativities between the site value of the landholdings was as would be expected if the site values had been generated on the basis of the actual landholdings. The assessments did not on their face disclose the duplication error. ACN submits that the judge should have held that it was not required to second-guess calculations made by the Commissioner that were not explained on the face of the assessments and when no indication had been given to it that any such inquiry was warranted or necessary. In particular, ACN submits the judge was entitled to, and should, have had regard to the fact that the duplication error was not identified by the Commissioner for 22 years. Moreover, it was significant that as soon as ACN was put on notice of the duplication error, it immediately took steps to investigate and claim the excess amount.

233 We accept that there was no evidence before the judge as to any information, by returns or otherwise, that had been supplied by ACN to the Commissioner. We also accept that the Commissioner has multiple avenues by which he can obtain valuation information under the Act. A taxpayer is not to be taken to know how in any instance the Commissioner obtains the information he relies upon. In particular, ACN had no knowledge at the relevant time that the Commissioner was basing his information upon Council valuations as opposed to, for example, valuations by the Valuer-General, which he is also permitted to draw upon.[287] Nor is a taxpayer to be taken to know what calculations are performed within the State Revenue Office on the basis of which the Commissioner issues assessments.

234 Moreover, it is apparent from the observations made by the New South Wales Court of Appeal in Sze Tu v Lowe[288] that, in some circumstances, before it can be said that a person has failed to exercise reasonable diligence in the context of the postponement of a limitation period, the person needs to be alerted to the utility of uncovering information, especially where to do so would be onerous and costly.

235 Tu concerned an alleged partnership between family members. The partnership engaged in the business of operating a grocery store and a butchery business. The businesses were operated by the father (Kut Sze Tu ('KST')) as family businesses and were eventually sold. KST purchased three properties and registered them in his name and the names of some of his children. The properties were purchased without finance. It was alleged that KST stole money from the partnership to purchase the properties. KST died intestate.

236 Proceedings were commenced for, amongst other things, a declaration that a partnership existed; an order winding up the partnership; a declaration that the properties were held on trust for the partnership; and an order for accounting to be undertaken in respect of the profits of the partnership. The defendants contended that there was no partnership or that the alleged partnership had been a 'sham', and that some claims were time barred by reason of the Limitation Act 1969 (NSW) (directly or by analogy).[289] At the trial on liability Smart AJ held that the claims were not defeated by any of the defences pleaded.[290] On appeal, Gleeson JA (with whom Meagher and Barrett JJA agreed) relevantly upheld the finding of Smart AJ that the claim to recover trust property was not statute-barred because the limitation period of 12 years would only run from the discovery of facts giving rise to the cause of action (November 2001).[291] Smart AJ had held that the cause of action to recover trust property was suspended until at least November 2001 because the relevant parties could not with reasonable diligence have discovered the facts giving rise to the relevant cause of action before that date.[292] The proceeding was commenced on 7 November 2005[293] and therefore within time.

237 Significantly, Smart AJ held that in determining whether reasonable diligence could have been exercised to uncover information about the purchase of the properties or whether they had been purchased with partnership funds, it was relevant to take into account that the cost of pursuing earlier suspicions would have been significant as a full audit would have been expensive; likely to have caused upheaval in the family; and the outcome was unknown. He also held that '[c]ollating and analysing all the information and evaluating it and the conclusions which should be drawn would take some time. To begin such an onerous and detailed exercise the plaintiffs needed to be alerted that it was likely to be useful'.[294] This finding was challenged on the basis that it reflected a wrong approach and took into account irrelevant considerations. Gleeson JA rejected the contention. He said:

The cost of pursuing suspicions is undoubtedly relevant to whether Geoffrey exercised reasonable diligence to discover the facts at that time. Further, in the context of a partnership between family members, the likelihood of a family upheaval, where the outcome of a full audit was unknown, was also relevant to whether Geoffrey had exercised reasonable diligence to discover the facts in December 1978. Finally, there was no error in Smart AJ finding that, before undertaking the onerous task of collecting and analysing information, Geoffrey and Mary needed to be alerted that it was likely to be useful.[295]

238 In our view, it is similarly relevant here that there was nothing to alert ACN, or to put it on inquiry, that an onerous and time-consuming task of collecting and analysing information would have any utility. The duplication error was hidden on the assessments. The error continued over the entire period of ACN's ownership. ACN responded to the assessments in the manner in which the Commissioner would no doubt expect; namely, by making the payments demanded with respect to the two properties without querying the site value recorded on the assessments. We consider that without anything to alert ACN to the likely inaccuracy of the assessments, ACN could not with reasonable diligence have discovered the duplication error or the mistake under which it paid the excess amount. With respect to her Honour, we consider that in these circumstances she ought not to have concluded that ACN could, with reasonable diligence, have discovered the mistake. We consider that ACN is entitled to the benefit of the extension provided by s 27 of the Limitations Act.

239 ACN clarified on the hearing of the appeals that, in respect of the mandamus proceeding, it sought compound interest, not from the date on which the payments that made up the excess amount were made but from the date when the Commissioner appreciated the existence of the duplication error and determined to retain the excess amount nonetheless. ACN submits that the relevant date is the date of the constructive refusal to amend, on or about 3 December 2012.[296] It seeks simple interest pursuant to s 58 of the Supreme Court Act from the date the payments were made.

240 We consider that simple interest should be awarded pursuant to s 58 of the Supreme Court Act from the date the payments were made that constituted the excess amount. We consider that, while strictly speaking the mandamus proceeding is a proceeding for the enforcement of a statutory duty, in the particular circumstances the proceeding is tantamount or analogous to a proceeding for the recovery of money and that a sum certain has been recovered, namely, $363,680.

241 We also consider that it is appropriate to award compound interest in the mandamus proceeding from 15 August 2013, the date of the Commissioner's actual refusal to amend the assessments, which we have concluded amounted to an act of conscious maladministration. We regard the circumstances surrounding the actual refusal to amend as exceptional and such as to support an order for compound interest.

242 ACN's claim for restitution has had a limited role in the appeals.[297] The claim has only served to establish in the mandamus proceeding the requirement of an antecedent liability, which we consider may not be necessary in any event. Given that limited role, it is unnecessary to determine whether ACN would be entitled to compound interest on the restitution claim.[298]

Conclusion on the mandamus application/appeal

243 For the reasons we have given, on the mandamus appeal, we would grant leave to appeal and allow the appeal.

244 The orders made below should be set aside and in lieu thereof the Court should make an order in the nature of mandamus directing the Commissioner to exercise his power under s 19 of the Act to issue amended assessments for the 19902002 land tax years (inclusive) and to give effect to those amendments by refunding the excess amount to ACN.

245 With respect to the question of interest, we consider that simple interest should be awarded on each overpayment that made up the excess amount from the date each payment was made, pursuant to s 58 of the Supreme Court Act, with compound interest being awarded from 15 August 2013.

Conclusion on the restitution application/appeal

246 On the restitution appeal, for the reasons we have given, we would grant leave to appeal, allow the appeal, and set side the orders below. Given the orders that will be made on the mandamus appeal, any further relief is unnecessary.[299]

[1] The applications for leave to appeal were heard at the same time as the appeals.

[2] The relevant Act that applies to each of the 1990-2002 land tax assessments is the Land Tax Act 1958 (Act No 6289/1958) (Version No 131, incorporating amendments as at 30 November 2005).

[3] See [60] below. We set out the relevant statutory framework at [52]-[77] below.

[4] Proceeding S CI 2013 1395, the appeal from which is S APCI 2015 0029.

[5] The amount at issue is $363,680. See [44] below.

[6] Proceeding S CI 2013 1396, the appeal from which is S APCI 2015 0030.

[7] ACN 005 057 349 Pty Ltd v Commissioner of State Revenue [2015] VSC 76 ('Reasons'). Her Honour gave joint reasons in dismissing both proceedings.

[8] We refer to 'the appeals' in what follows.

[9] The term 'duplication error' and the other terms used in the summary are explained in the course of the judgment.

[10] The outstanding claims relate only to the 1990-2002 land tax years.

[11] [1971] HCA 12; (1971) 127 CLR 106 ('Finance Facilities').

[12] (2008) 237 CLR 146 ('Futuris').

[13] [1994] HCA 61; (1994) 182 CLR 51 ('Royal Insurance').

[14] The facts are essentially agreed between the parties: Reasons [5]. The evidence before the judge was given by affidavit and there was no cross-examination.

[15] For convenience, this is referred to below as land ID reference 27424, except when necessary.

[16] For convenience, this is referred to below as land ID reference 598039, except when necessary.

[17] ACN transferred the two properties to Streetriver in December 2007.

[18] ACN became the owner of Lot 1 Lodge Plan 27424 ('2 Ottawa Road') in 1986 and acquired Lot 1 Title Plan 598039 ('65 Albany Road') in 1988.

[19] The Commissioner was unable to produce at trial notices of assessments for the 1990-2005 land tax years: Reasons [69].

[20] In Table 1 there is a reference to TP598038 rather than TP598039 in respect of 65 Albany Road. This appears to be a slip.

[21] ACN relied on the ratio between the site values, as represented on the assessments, as one of the reasons why it could not with reasonable diligence have discovered the duplication error or the mistake under which it made excess payments. See [232] below.

[22] Section 8 of the Act provides that land tax is assessed on the total unimproved value of the land at midnight on the 31st of December immediately preceding the year for which the tax is assessed. See [52] below.

[23] See [14] above.

[24] Reasons [146]. See [97] below.

[25] The Commissioner is permitted to use valuations made by a municipal council pursuant to s 16 of the Act. See [56] below.

[26] As noted at n 14 above. Warren v Coombes [1979] HCA 9; (1979) 142 CLR 531, 551; Fox v Percy [2003] HCA 22; (2003) 214 CLR 118, 127 [27]. We also reject the submission of the Commissioner that the question of whether the assessments are excessive cannot be agitated in these proceedings as 'the matter is closed'. See [145]-[162] below. See also Reasons [188]; see [108] below.

[27] As we discuss at [35] and [43] respectively below, the Commissioner accepted objections and made refunds for the 2006 and 2007 land tax years with interest and issued an ex gratia payment with respect to the 2003-2005 land tax years.

[28] See [11] above.

[29] He later issued amended assessments deleting '65 Albany Road' for the 2006 and 2007 land tax years. See [36]-[40] below.

[30] Ngo's evidence was that he made the refund request in relation to the 2007 year only because he had been told by Pritchard that the Commissioner was only obliged to provide refunds within a five year period from the date the payment had been made and it was unlikely that refunds would be provided outside this period.

[31] By letter dated 24 October 2012 to Ngo, the Commissioner indicated that he exercised his discretion pursuant to s 100 of the Taxation Administration Act 1997 to accept the out of time objections in relation to the 2006 and 2007 land tax assessments.

[32] See [7] above.

[33] See [35] above.

[34] See [35] above.

[35] When the Commissioner informed ACN, by letter dated 17 January 2013, that ACN was entitled to a refund of the amounts $110,635 in respect of the 2006 land tax year and $103,800 in respect of the 2007 land tax year, he also informed ACN that there had been a 2008 assessment notice issued for '65 Albany Road' on 8 February 2008 and this had been fully settled by a payment of $157,230 on 20 June 2008. The assessment was subsequently withdrawn when a Notice of Acquisition was lodged in October 2008 in respect of the transfer of '65 Albany Road' to Streetriver in December 2007. The Commissioner acknowledged there had therefore been a further overpayment of $157,230 which he refunded. This 2008 assessment notice would appear to be distinct from the assessment notice for the 2008 land tax year issued to Streetriver on 28 November 2008 for $157,230 which referred to the two properties and in respect of which the Commissioner acknowledged an overpayment in the 23 March 2012 email.

[36] Section 19 empowers the Commissioner to amend assessments from time to time. It is set out in full at [60] below.

[37] These sums reflect those in Table 4 for their respective land tax years.

[39] See [30]-[31] above.

[40] See [185]-[189] below: '(4) What was the character of the alleged mistake?'

[41] We consider that the letter of 15 August 2013, in the circumstances of the case, amounts to an implied admission that the duplication error occurred in each of the 1990-2002 land tax years, that the assessments for the 1990-2002 land tax years were thereby inaccurate, and that he wrongly collected taxes that were not otherwise due. See [155]-[158] below.

[42] Emphasis added. Section 90AA provides for a limitation period of three years for the bringing of an application to the Commissioner for a refund. Further time constraints apply before proceedings can be brought. Section 90AA is set out in full at [71] below.

[44] See [41] above.

[45] See [49] above.

[46] See [37] and [39] respectively.

[47] Section 9(1)(d).

[48] Section 9(1)(ga).

[49] See ss 17 and 18. See [58] and [59] below.

[50] Valuation of Land Act s 2. This was the definition of 'rating authority' included in the Valuation of Land Act between 1990-2002.

[52] Local Government Act 1989 s 3. The definition of 'council' did not change between 1990 and 2002.

[53] Part IIB concerns the taxation of transmission easements.

[54] ACN contends that the payment of the excess amount was not a 'sum payable for tax'. This was relied upon to criticise the judge's view that ACN received good consideration when it paid the excess amount because its statutory debt was discharged. See [197]-[198] below.

[55] See [49] above.

[56] The Commissioner contended before the judge that if s 5(1) of the Limitations Act is relevant, it is s 5(1)(a) because when the Limitations Act commenced, in 1958, common law restitutionary actions for mistake were regarded as founded on a 'contract implied by law' or 'quasi contract': see Reasons [154], [156]. He also said ACN should not have the benefit of any postponement under s 27. ACN contended that if s 5(1) is relevant, it is s 5(1)(d) together with the benefit of a postponement under s 27.

[57] Section 20A was amended to its current form by the Limitation of Actions (Amendment) Act 2004 (No 8/2004) which commenced on 4 March 2004 while s 90AA was inserted by the State Taxation (Further Amendment) Act 1993 (No 104/1993). An earlier s 20A had been introduced in 1961 by the Limitation of Actions (Recovery of Imposts) Act 1961 for the recovery of taxes 'paid under the authority or purported authority of any Act'. It made no mention of payments made under a mistake. It was replaced by a new s 20A introduced by the Limitation of Actions (Amendment) Act 1993 (No 102/1993) which from 15 October 1993 applied to proceedings for the recovery of money 'paid by way of tax or purported tax under a mistake (either of law or fact)'. It was enlarged in 2004 to include the recovery of money paid 'by way of an amount that is attributable to tax or purported tax ... or under colour of authority'. See Reasons [49]-[51].

[58] Reasons [61]. The formulation of the issues identified by the judge has been modified to reflect the definitions we have already adopted.

[59] That is, the regime under ss 24A-38 of the Act.

[60] That is, the regime under ss 90AA of the Act.

[61] The judge defined the Act as the 'LTA 1958'.

[63] Applying Thiess v Collector of Customs [2014] HCA 12; (2014) 250 CLR 664, 671 [22].

[65] [2011] VSCA 89; (2011) 31 VR 397, 408 [48] ('Gas Ban').

[67] As mentioned at n 57, s 90AA was inserted by s 22 of the State Taxation (Further Amendment) Act 1993.

[68] Reasons [80] quoting from Victoria, Parliamentary Debates, Legislative Assembly, 21 October 1993, 1254 (Alan Stockdale, Treasurer).

[69] See [74] above.

[70] Reasons [81], Gas Ban [2011] VSCA 89; (2011) 31 VR 397, 409 [53].

[71] See [150]-[153] below.

[72] This was despite there being no assessments for the years 1990-2002 produced by the Commissioner. ACN submits that the judge erroneously emphasised s 20 in circumstances where the Commissioner was unable to rely upon it. However, the judge noted that in some of the cases concerned with similar legislative regimes which have held an objection regime to be exclusive, the Commissioner placed no reliance on a conclusive evidence provision: Reasons [87] with respect to Hoare Bros Pty Ltd v Federal Commissioner of Taxation (1996) 62 FCR 302 ('Hoare Bros'), approved by the High Court in Deputy Commissioner of Taxation v Broadbeach Properties Pty Ltd [2008] HCA 41; (2008) 237 CLR 473. See also Futuris (2008) 237 CLR 146, 166 [62]. We consider that the judge focused upon s 20 as part of the statutory scheme, which she was entitled to do, and did not impermissibly rely upon s 20 as though it rendered conclusive assessments which the Commissioner could not produce.

[73] Reasons [83]-[85] (emphasis added) (citation omitted).

[74] See [80(3)] above.

[75] Reasons [113]. See [90] below.

[77] Ibid [65], [87]-[105]. She referred, for example, to the federal regime under Part IVC of the Taxation Administration Act 1953 (Cth) (see Futuris (2008) 237 CLR 146; Deputy Commissioner of Taxation v Richard Walter Pty Ltd [1995] HCA 23; (1995) 183 CLR 168; Hoare Bros (1996) 62 FCR 302); stamp duty (Stamp Act 1921 (WA); Stamp Act 1894-1982 (Qld), Stamp Duties Act 1923 (SA) and Commissioner of State Taxation (WA) v Bayswater Hire Cars Pty Ltd (1989) 20 ATR 1606; O'Sullivan v Commissioner of Stamp Duties [1984] 1 Qd R 212, and Corfu Clothing Co Pty Ltd v Commissioner of Stamps (1988) 48 SASR 105, respectively) and payroll tax (Phibbs v Dale (unreported, Supreme Court of Victoria, Menhennitt J, 8 June 1978)).

[79] Ibid n 45. See also Reasons [1], [62], [70], [107], n 151.

[80] See [68] above.

[81] See [66] above.

[82] See [69] above.

[84] See [80(2)] above.

[85] See [71] above.

[87] See [76] above. As mentioned at [79] above, the primary position of ACN was that s 20A did not apply to its proceedings for restitutionary relief, the proceedings not being one for the recovery of money paid by way of tax or purported tax. As an alternative, it put a secondary position that, if s 20A did apply, it was subject to the postponement provision under s 27 of the Limitations Act.

[88] Reasons [124]-[125] (footnote omitted).

[89] The judge took the view that it was difficult to see how s 20A(1)(b) could apply to pick up the three-year limitation period in s 90AA because of 'the limited scope for commencing a proceeding under s 90AA' which left potentially only the 12-month limitation period under s 20A(1)(a), which was clearly not satisfied so that 'unless s 27 is enlivened, the proceeding would be barred': Reasons [134].

[90] See [77] above.

[91] See [79] above.

[92] Reasons [143] (emphasis in original).

[93] Ibid n 151. See [90] above.

[94] Reasons [144] (emphasis added) (footnote omitted).

[95] See [185]-[189] below.

[96] See [30]-[31], [48] above.

[97] On the issue of the ratio between the relative values of the two properties see [19] above.

[98] Reasons [145]-[149] (footnotes omitted).

[101] Ibid [160]. The judge appeared to suggest that, if s 5(1) was applicable, it would be s 5(1)(a) ('contract implied by law') rather than s 5(1)(d) ('[a]ctions to recover any sum recoverable by virtue of an enactment'): Reasons [160].

[102] Reasons [162]. See [145]-[161] below.

[103] See [49] above.

[104] (1880) 5 AC 214 ('Julius').

[105] Ibid 222-3, as quoted in Reasons [170].

[106] The Stamps Act 1978 (No 9208) introduced a number of amendments to the Principal Act (the Stamps Act 1958) which included substituting this form of wording for s 111.

[107] See Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 62, 84.

[108] In Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, the terms 'Comptroller' and 'Commissioner' are used interchangeably in the judgments. In discussing Royal Insurance we use the term 'Commissioner of State Revenue' or 'the Commissioner'.

[109] See [165] below.

[110] Reasons [173]-[174] (citations omitted). See also [177] below.

[111] [2002] NTCA 10; (2002) 171 FLR 166 ('Tourism Holdings') (Northern Territory Court of Appeal).

[112] [1926] HCA 30; (1926) 38 CLR 289 ('Agricultural Service Engineers'), affirming the decision of the Supreme Court of South Australia, R v Commissioner of Taxes (SA); ex parte Commonwealth Agricultural Service Engineers Ltd [1926] SAStRp 28; [1926] SASR 168.

[113] (1985) 81 FLR 293 ('Boyded').

[115] Reasons [187]-[189] (footnotes omitted).

[116] Reasons [191] (footnotes omitted).

[117] Ibid [192]-[194] (citations omitted).

[118] See [49] above.

[119] Reasons [199]-[203] (footnotes omitted).

[120] The relief sought was formulated as follows: 'A. An order for mandamus or other orders on judicial review directing the defendant: (a) to issue amended land tax assessments to the plaintiff for the 1990-2002 land tax years inclusive; and (b) to refund to the plaintiff the land tax which was overpaid by the plaintiff for the 1990-2002 land tax years'.

[124] Ibid [219]. This was calculated as at 10 October 2013.

[126] By the email of 23 March 2012. See [11] above.

[127] [1998] HCA 28; (1998) 194 CLR 355 ('Project Blue Sky').

[129] See [134] below.

[130] See [60] above.

[131] [2014] HCA 13; (2014) 307 ALR 174 ('Emmerson').

[132] Section 44(1) relevantly provided: 'The Supreme Court may, on application by the DPP, make a restraining order in relation to the property of a person named in the application if: (a) the person has been charged, or it is intended that within 21 days after the application the person will be charged, with an offence that, if the person is convicted of the offence, could lead to the person being declared to be a drug trafficker under section 36A of the Misuse of Drugs Act'.

[133] Emmerson [2014] HCA 13; (2014) 307 ALR 174, 192 [68] (footnotes omitted) (emphasis in original) (French CJ, Hayne, Crennan, Kiefel, Bell and Keane JJ).

[134] (2009) 240 CLR 319, 373 [121] ('International Finance Trust').

[135] [1971] HCA 12; (1971) 127 CLR 106.

[136] Ibid 134-5 (citations omitted). Barwick CJ agreed with Windeyer J: at 128. Owen J adopted a similar construction of s 46(3): at 138-9. McTiernan J was in dissent.

[137] The Criminal Assets Recovery Act 1990 (NSW). The relevant provision, s 10(3) was in these terms: 'The Supreme Court must make the order applied for under subsection (2) [a restraining order] if the application is supported by an affidavit of an authorised officer stating that: (a) in the case of an application in respect of an interest referred to in subsection 2(a) - the authorised officer suspects that the person has engaged in a serious crime related activity or serious crime related activities and stating the grounds on which that suspicion is based, and (b) in the case of an application in respect of any other interest - the authorised officer suspects that the interest is serious crime derived property because of a serious crime related activity or serious crime related activities of a person and stating the grounds on which that suspicion is based, and the Court considers that having regard to the matters contained in any such affidavit there are reasonable grounds for any such suspicion'.

[138] (2009) 240 CLR 319, 373 [121] (citations omitted) (emphasis in original). Hayne, Crennan and Kiefel JJ were in dissent on the result with respect to the constitutional validity of s 10.

[139] Mildren and Thomas JJ and Priestley A-J.

[141] Tourism Holdings [2002] NTCA 10; (2002) 171 FLR 166, 168 [4] (emphasis added). Priestley A-J agreed with Mildren J on the cross-appeal (at 184 [62]). Section 97(3) expressly provided for refunds to be provided in the event of overpayment: 'Where, by reason of an amendment to an assessment, a person has overpaid duty or tax, the amount of duty or tax shall be refunded'.

[143] Ibid 172 [16] (emphasis added). The observation that after three years 'the matter is closed' is clearly a reference back to the three-year period specified in s 97(1).

[145] Agricultural Service Engineers [1926] HCA 30; (1926) 38 CLR 289, 294, quoted in Tourism Holdings [2002] NTCA 10; (2002) 171 FLR 166, 183 [55].

[146] Tourism Holdings [2002] NTCA 10; (2002) 171 FLR 166, 183 [55].

[148] (1985) 81 FLR 293, 297 (Boyded).

[151] See [155]-[157] below.

[152] D'Emden v Pedder [1904] HCA 1; (1904) 1 CLR 91, 110.

[153] Tourism Holdings [2002] NTCA 10; (2002) 171 FLR 166, 172 [16]. See also Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 87 (Brennan J).

[154] See [36]-[40] above.

[155] See [11]-[12] above.

[156] Reasons [78]-[80], [187]-[203], [209]-[211]. See [83] and [108] above.

[157] See Tourism Holdings [2002] NTCA 10; (2002) 171 FLR 166, 172 [16]. See [136] above.

[158] Land Tax (Amendment) Act 1974 s 2.

[159] See the second reading speech for the State Taxation (Amendment) Bill 1992 (Victoria, Parliamentary Debates, Legislative Assembly, 6 November 1992, 566 (Alan Stockdale, Treasurer)).

[160] Second reading speech for the State Taxation (Further Amendment) Bill 1993 (Victoria, Parliamentary Debates, Legislative Assembly, 21 October 1993, 1254 (Alan Stockdale, Treasurer)). See [84] above.

[161] (1992) 23 ATR 528.

[162] Second reading speech for the State Taxation (Further Amendment) Bill 1993 (Victoria, Parliamentary Debates, Legislative Assembly, 21 October 1993, 1254 (Alan Stockdale, Treasurer)).

[163] Second reading speech for the Limitation of Actions (Amendment) Bill 1993 (Victoria, Parliamentary Debates, Legislative Assembly, 21 October 1993, 1207 (Alan Stockdale, Treasurer)).

[164] See [85] above.

[165] See [60] above.

[167] (2008) 237 CLR 146.

[168] In proceedings under Part IVC the Court does not have jurisdiction to determine if an assessment is invalid because of jurisdictional error due to conscious maladministration: Gashi v Federal Commissioner of Taxation [2013] FCAFC 30; (2013) 209 FCR 301, 310 [41].

[169] Section 175A provided: 'A taxpayer who is dissatisfied with an assessment made in relation to the taxpayer may object against it in the manner set out in Part IVC of the Taxation Administration Act 1953 ['the Administration Act']'. Section 177(1) of the ITAA was a conclusive evidence provision in relation to the production of a notice of assessment.

[170] Futuris (2008) 237 CLR 146, 157 [24] (Gummow, Hayne, Heydon and Crennan JJ).

[171] For example, see Roberts v Deputy Commissioner of Taxation [2015] FCA 238.

[172] Futuris (2008) 237 CLR 146, 164-5 [55].

[173] Ibid 165 [56] (citations omitted).

[174] See [111] above.

[175] See [49] above.

[176] See especially [28]-[31] above.

[177] (2008) 237 CLR 146, 165 [58]-[59].

[178] Gas Ban [2011] VSCA 89; (2011) 31 VR 397, 408 [49].

[179] We consider that, in any event, he was wrong to rely upon s 90AA. See [211]-[225] below.

[180] See [155] above.

[182] See [49] above.

[183] See Futuris (2008) 237 CLR 146, 165-6 [60].

[184] Ibid 165 [56], in the context of holding that s 175 of the ITAA does not protect from the reach of the constitutional writs a jurisdictional error founded upon conscious maladministration.

[185] Ibid 157 [25] 164-5 [55]; Gashi v Federal Commissioner of Taxation [2013] FCAFC 30; (2013) 209 FCR 301, 310-11 [43]; Hoare Bros (1996) 62 FCR 302, 313-4 (Black CJ, Einfeld and Sackville JJ); Gas Ban [2011] VSCA 89; (2011) 31 VR 397, 408 [49] in the context of State payroll tax legislation.

[186] See [139] above.

[187] This was submitted for the purpose of establishing the date from which compound interest was sought on the mandamus case.

[188] The predecessor of s 111 provided: 'If after any duty has been paid by any company person or firm of persons under the provisions of this subdivision the Comptroller of Stamps, on application made to him within twelve months after such payment, is satisfied that such overpayment has been made shall apply to the Treasurer of Victoria for a refund to such company person or firm of persons of the duties overpaid, and the Treasurer shall without further or other authority than this Act refund the amount thereof to the company person or firm by whom the overpayment has been made or to any person acting in its his or their behalf'. (emphasis added).

[189] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 64.

[191] Ibid 64-5 (citations omitted)(emphasis added).

[192] He rejected the application of s 20A as it stood at the time when it made no reference to payments made under a mistaken belief, as it does now: Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 80. See [76] and n 57 above.

[193] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 65 (citations omitted).

[194] [1992] HCA 48; (1992) 175 CLR 353 ('David Securities').

[195] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 66-7 (citations omitted).

[198] See [165] above.

[199] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 80-1 (citations omitted) (emphasis added).

[200] See [104] above.

[201] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 84.

[203] See n 188 above.

[204] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 85.

[206] Ibid 87. Brennan J took the view that before the introduction of the express appropriation power in s 166D, s 111(1) operated as an implied power of appropriation.

[208] See Susan Butler (ed), Macquarie Dictionary (Macquarie Dictionary Publishers, 6th ed, 2013).

[209] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 87 (emphasis added).

[211] See [103] above.

[213] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 88 (citations omitted) (emphasis added).

[214] See [171] above.

[215] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 89 (citation omitted) (emphasis added).

[218] See, for example, [88] and [90] above.

[219] See [185]-[189] below.

[220] Section 20A was then in the form when it made no mention of mistake. See Reasons [49], n 26. See n 57 above.

[221] With respect to the payment affected by the 1987 Act, Brennan J held that although prima facie it would have been governed by s 20A, impliedly s 20A was excluded by the retrospective operation of the 1987 Act and thus, being a statutory liability, s 5(1)(d) of the Limitations Act applied, namely, '[a]ctions to recover any sum recoverable by virtue of an enactment': Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 92.

[222] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 92 (emphasis added). Dawson J, in dissent, held that a finding by the Commissioner that an overpayment had been made was sufficient to give rise to a duty under s 111 to refund: Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 97-8, 99, 102.

[223] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 92.

[224] See [164] and [60] above respectively.

[225] See [139] above.

[226] Reasons n 45. See [90] above. See also Reasons [1], [62], [70], [107], n 151.

[227] See [44] above.

[228] See [48] above.

[229] See [47] (emphasis added).

[230] See [198] below.

[231] See [31] above.

[232] It might be argued that this is in part a mistake of fact, not law. In any event, this would not be material to the issue of restitutionary relief.

[233] See [31] and [189] above.

[234] [1994] HCA 61; (1994) 182 CLR 51, 75 (citation omitted). See also Brennan J at 89 and David Securities [1992] HCA 48; (1992) 175 CLR 353, 378-9.

[235] See [185]-[189] above.

[236] Australian Financial Services and Leasing Pty Ltd v Hills Industries Ltd [2014] HCA 14; (2014) 253 CLR 560, 593 [67], 605 [106].

[237] [1992] HCA 48; (1992) 175 CLR 353, 392.

[238] See [167] above.

[239] See [197] below.

[240] Reasons [200]. See [111] above. See Royal Insurance Australia Ltd v Comptroller of Stamps (Vic) (1992) 23 ATR 528, 548 (Hedigan J).

[241] See [66] above.

[242] We do think, however, that the payment of the excess amount was a sum 'attributable to ... purported tax' within s 20A(1) of the Limitations Act. See [217] below.

[243] See [167] above.

[244] See [196] above.

[245] We consider the question to be open. See [183] above.

[246] See [155]-[159] above.

[247] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 92.

[249] (1996) 62 FCR 347 ('Chippendale Printing').

[251] See [177] above.

[252] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 88.

[253] See [178]-[182] above.

[254] That is, the payments other than those affected by the 1987 Act. See [163], [178], [179] above. While the judge aligned the payment of the excess amount with payments made under the 1987 Act we consider her Honour was wrong to do so. See [180] above.

[255] Royal Insurance Australia Ltd v Comptroller of Stamps (Vic) (1992) 23 ATR 528, 530, 535, 549.

[256] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 103.

[257] (1996) 62 FCR 347, 368-9 (emphasis added).

[258] In effect ACN's proceeding for restitution served to establish the requirement that there was here an antecedent liability, if such a requirement is necessary.

[259] See [79] above.

[260] See [157] above.

[261] Section 90AA(8). See [71] above.

[262] Section 20A then did not include the words 'under a mistake (either of law or of fact)'. See n 57 above.

[263] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51, 80.

[264] See [75] above.

[265] See [76] above.

[266] (1992) 23 ATR 528.

[268] See [212] above.

[269] See n 57 above.

[270] As her Honour noted (Reasons n 25) the decision of the High Court in Royal Insurance was delivered on 7 December 1994, after s 90AA had been inserted into the Act by the State Taxation (Further Amendment) Act 1993 and after the new s 20A had been inserted into the Limitations Act by the Limitation of Actions (Amendment) Act 1993. It thus cannot be inferred that the Victorian Parliament, in enacting those provisions, had the benefit of the reasoning of the High Court.

[271] See [76] above.

[272] See [93] above.

[273] In particular the expansion of s 20A to amounts that are 'attributable to ... purported tax', the language we consider applies here, occurred in 2004. See n 57 above.

[274] As s 20A is also specifically addressed to the recovery of tax or purported tax we also consider that it impliedly repeals or restrictions the operation of s 67 of the Act. See [70] above.

[275] Royal Insurance [1994] HCA 61; (1994) 182 CLR 51. Brennan J said (at 92): 'The relevance of the limitation periods is that they mark the periods during which a legal liability to refund would have been enforceable by action, if s 111(1) had not transformed the cause of action into a right to performance by the Commissioner of her duty to exercise her power to refund'.

[276] Commissioner of Police (NSW) v Eaton [2013] HCA 2; (2013) 252 CLR 1, 28 [78] (Crennan, Kiefel and Bell JJ). See also Gageler J at 33 [98]. It should be noted that both the Act and the Limitations Act are statutes enacted by the Victorian Parliament and no potential inconsistency between a State Act and a Commonwealth Act arises.

[277] Or failed to apply it in effect as credit against another liability the applicant owes to the State under an Act of which the Commissioner has the general administration: s 90AA(3)(b) and s 90AA(6)(d). Partial refunds are also taken into account.

[278] That is, a person who has lodged an application for the refund of an amount in accordance with sub-s (2) of s 90AA.

[279] See [216] above.

[280] See [10]-[11] above.

[281] On 21 March 2013 ACN filed the Writ in the restitution proceeding and an Originating Motion seeking relief in the nature of mandamus. Reasons [21]. See [45] above.

[282] See [77] above.

[283] The other two alternatives under s 27 (being an action based on (a) fraud or (b) being concealed by fraud) are clearly not satisfied.

[284] See [20] above.

[285] See Table 1 at [18] and [97] above.

[286] See [18]-[19] above.

[287] The Act s 16. See [56] above.

[288] [2014] NSWCA 462 ('Tu') (Meagher, Barrett and Gleeson JJA).

[289] The relevant section was s 47 of the New South Wales Limitation Act which relevantly provided: '(1) An action on a cause of action: ... (c) to recover trust property, or property into which trust property can be traced, against a trustee or against any other person ... is not maintainable by a trustee of the trust or by a beneficiary under the trust or by a person claiming through a beneficiary under the trust if brought after the expiration of the only or later to expire of such of the following limitation periods as are applicable: (e) a limitation period of twelve years running from the date on which a plaintiff or a person through whom the plaintiff claims first discovers or may with reasonable diligence discover the facts giving rise to the cause of action and that the cause of action has accrued'.

[290] The trial was limited to eight issues of liability. After some further documents were discovered, there was a 'fresh trial' by Gzell J limited to three issues which had not been determined by Smart AJ and which did not revisit the defences.

[291] Tu [2014] NSWCA 462, [389].

[294] Lowe v Pascoe [2010] NSWSC 388, [507(f)].

[295] Tu [2014] NSWCA 462, [411].

[296] This is the date of the letter from ACN requesting amendments to the assessments for the 1990-2002 land tax years. See [41] above.

[297] See [182]-[183], [203]-[206] above.

[298] This issue was not fully argued by the parties. We note that while ACN made submissions on the issue, the Commissioner made it clear that he did not wish to be heard in respect of interest on the restitution claim. Rather, Senior Counsel for the Commissioner indicated that he reserved the right to argue at another level that compound interest was not available in Australia for a restitution claim. He did the same at trial: see Reasons n 207. The absence of properly contested submissions on the issue reinforces our view, given our analysis of Royal Insurance, and given that the judge drew no conclusions on the issue, that it is unnecessary for us to determine what has become a hypothetical issue.

[299] Save for the question of the costs of the restitution appeal on which the parties will be heard at the time of delivery of judgment.