Child Support - care percentage determination - revocation and remaking of care percentage determinations - objection disallowed - bifurcated determination based on agreement of further change to care arrangements - Tribunal is not a primary decision making body - whether Child Support Registrar v DQFY [2023] FCA 601 contains binding statement of principle - Child Support Registrar v DQFY [2023] FCA 601 does not contain binding statement of legal principle - legislative scheme mandates each care determination be revoked before new determination made - assessment of pattern of care in care period - agreement of parties as to subsequent change of care outside care period legally immaterial - Child Support Registrar v BKCZ [2023] FCA 1109 applied - Tribunal must take into account evidence of events after notification - BKZC does not authorise multiple care percentage determinations or primary decision making in the Tribunal - decision under review set aside insofar as second care determination made

Child Support (Assessment Act) 1989

Child Support (Registration and Collection) Act 1988

Child Support Registrar v DQFY [2023] FCA 601

Child Support Registrar v CMU23 [2024] FCA 109

Re Brian Lawlor Automotive Pty Ltd v Collector of Customs (NSW) (1978) 1 ALD 167

LJSS v KBNY and Child Support Registrar (9 June 2023) VID511/2022 (notation to order by consent)

Child Support Registrar v BKCZ [2023] FCA 1109

1. Mr LTWS and Ms CNTQ are the parents of two children, in respect of whom a child support assessment is in place. For the purpose of calculating the child support liability under the scheme created by the Child Support Assessment Act 1989 (the Assessment Act), a care percentage determination reflecting 72% to CNTQ and 28% to Mr LTWS was in place when, on 17 April 2019, Mr LTWS contacted Services Australia to advise that the care arrangements had changed.[1]
2. Mr LTWS advised that the care of the children was taking place in accordance with a court order dated 21 January 2019, and the order translated to 142 nights' care per year (five nights per fortnight and half the school holidays). On 27 April 2019, Services Australia discussed the matter with Ms CNTQ, who agreed, and so Services Australia revoked the existing care percentage determinations and replaced them with care determinations reflecting the children as 62% in Ms CNTQ's care and 38% in Mr LTWS' care from 31 January 2019.
3. Both parents were notified of that change to the care percentages by letter dated 27 April 2019[2].
4. On 29 March 2023 (that is, nearly four years later) Mr LTWS lodged an objection to the decision of 27 April 2019[3]. Mr LTWS is recorded to have told Services Australia that the court order had stood for approximately 2 years, but then a private agreement commenced with 50/50 care. Mr LTWS is documented to have said that he could not remember the exact date but it had been at least 4 years.
5. On 25 May 2023, Ms CNTQ discussed the objection with the objection officer.[4] She is recorded to have said that through a verbal agreement, care of the children was 50/50 from 19 October 2020, and confirmed her position by letter dated the same day, although in her letter she stated the date the care changed was 12 October 2020[5]. Ms CNTQ did not agree that care had been 50/50 from four years prior.
6. On 14 July 2023, the objections officer disallowed Mr LTWS' objection[6], finding that both parents had agreed the change to the care percentages put in place on 27 April 2019 had been correct at the time. While noting the evidence of the parents that care was 50/50 from either '4 years earlier' or from '19 October 2020', the objection officer found that they could not be satisfied that the care was 50% for each parent at the date identified by Mr LTWS (31 January 2019). The objection officer noted that there had been no communication from either parent to notify a further change in care from 19 October 2020.
7. Mr LTWS applied to the Administrative Appeals Tribunal (AAT) for review on 7 August 2023.
8. On 15 January 2024, the AAT decided to vary the decision under review so that the decision to revoke the pre-existing care percentage determinations and replace it with the care percentage determinations of 38% and 62% was not changed, but noting that both Mr LTWS and Ms CNTQ had agreed that care had changed to 50% for each parent from 12 October 2020, revoked that care percentage determination from 23 March 2023 for Mr LTWS and 12 October 2020 for Ms CNTQ and replaced it with care percentage determinations of 50%.
9. In this way, the AAT had reviewed or otherwise made two primary care percentage determinations notwithstanding that the objection officer dealt with only one. It is apparent in this regard that the Tribunal was purporting to make a 'bifurcated' care percentage determination of the kind arguably approved of by the Court in Child Support Registrar v DQFY [2023] FCA 601 (DQFY). In that matter, the Court had dismissed an appeal by the Child Support Registrar on questions of law which relevantly including an assertion that the Tribunal in that matter had exceeded its jurisdiction or powers on review by making a second care percentage determination.S
10. The AAT also stated that the decision had effect from 29 March 2023, being the date of Mr LTWS' objection, correctly identifying the application of section 87AA of the Child Support (Registration and Collection) Act 1988 (the Registration and Collection Act). By making this statement, the AAT found the original decision had been made on 27 April 2019, and that Mr LTWS had sought review on 29 March 2023, and then considered the question of whether there were special circumstances that prevented Mr LTWS from objecting earlier. In finding that there were not, the AAT can also therefore be seen to have made a decision in respect of section 87AA of the Registration and Collection Act.
11. Mr LTWS applied to the AAT for second review at some stage after 15 January 2024 but prior to 15 May 2024.
12. On 14 October 2024, the Administrative Appeals Tribunal was abolished and the Administrative Review Tribunal commenced operations. Under the transitional provisions in the Administrative Review Tribunal (Consequential and Transitional Provisions No. 1) Act 2024 (the Transitional Act), applications for review that were not finalised by the Administrative Appeals Tribunal before 14 October 2024 were taken to be applications for review to the Administrative Review Tribunal (hereafter the Tribunal). The Transitional Act gives the Tribunal the authority to continue and finalise any aspect of the review not already completed.
13. A care percentage decision (within the meaning of the Registration and Collection Ac_t_) is an 'eligible social services decision' amenable to second review in the Tribunal: Part 5A of the Administrative Review Tribunal Act 2024.

1. In this matter, it is convenient to address the evidence and reach relevant, or potentially relevant findings of fact before discussing the applicable legislative framework and potentially binding case law.
2. As it happens, no factual dispute regarding the care percentages or the timing of changes to the care percentages falls for determination. The parties no longer have the differing views of relevant or potentially relevant facts that they once did.
3. Mr LTWS' position was that he did not cavil with the facts as found by the AAT relating to care periods or care percentages, but wished for the Tribunal to reconsider the exercise of discretion provided for in section 87AA of the Registration and Collection Act. It was submitted on behalf of Mr LTWS that the AAT's finding that care changed from 28%/72% to 38%/62% from 31 January 2019 should be accepted, as should the finding that care became 50%/50% from 12 October 2020.
4. Ms CNTQ's position was that the 50%/50% care definitely started on 12 October 2020, and no issue has ever been taken by Ms CNTQ with the care change of 31 January 2019.
5. In this way, other than the issue regarding the application of section 87AA of the Registration and Collection Act to the date of effect of the objection outcome and the exercise of discretion therein, there was no factual dispute between the parties.
6. Given the position of the parties, I find that the care of the children changed on 31 January 2019 from 28% / 72% to 38% / 62%, and then changed again from 38% / 62% to 50% / 50% from 12 October 2020, recognising that my finding in relation to 12 October 2020 may well ultimately be an observation beyond the scope of the review subject to my consideration of the legal framework and potentially applicable case law.
7. The relevance of the surviving issue therefore, that is, whether there were special circumstances that prevented Mr LTWS from lodging his objection within 28 days of notification, emerges for determination only if I may, at law, make that care percentage determination pertaining to 50%/50% care from 12 October 2020 (or recognise it as a bifurcation of the only care percentage determination), or indeed if I am bound to do so on the evidence before me. In this way, the question as to what in principle binds me in respect of DQFY, or whether DQFY is distinguishable becomes largely determinative of my approach to the remaining issue in dispute.
8. To put this another way, if DQFY is not to be understood as binding authority rejecting the Child Support Registrar's contentions that it is beyond jurisdiction to make the care determination or bifurcation in respect of 12 October 2020, then the question of the date of effect of the implementation of that bifurcation will not arise, because the decision on review must be (on the evidence of the parties) that the decision of the AAT is to be set aside and substituted with a decision that the objection (to the decision of 27 April 2019) is to be disallowed.
9. To the contrary, if the dismissal of the Registrar's appeal in DQFY means that I am bound to reject the Registrar's arguments in this regard, then the objection is to be allowed and the issue as to the date of effect of that outcome will need to be addressed.
10. It is necessary to recognise with some regret that the reasoning in this review and the matters it addresses become from this point technical, niche, and legally complex. I do understand, as is often the case in reviews of child support care determinations, that Mr LTWS feels that his child support liability should simply be made to reflect the actual care levels for the children from time to time, in accordance with the common factual position now advanced by the parties. I suspect Mr LTWS and perhaps also Ms CNTQ will be frustrated that I must approach the review by navigating the complexities of the making and revoking care determinations, considering differential dates of effect and limitations on the date of favourable review decisions, examine of judicial authority for binding principal and ensure that I stay within the confines of my jurisdiction, rather than simply bring into existence a child support liability that reflects the agreed history of the care arrangements.
11. Indeed, in Child Support Registrar v CMU23 [2024] FCA 109 (1 February 2024) the Court observed of the Assessment Act and adjacent provisions regulating care determinations:

[4] The elegant simplicity of s 84 of the Matrimonial Causes Act stands in marked contrast to the convoluted and Byzantine provisions which have, for some reason or other, commended themselves to Parliament and are presently found in the Assessment Act. It was put - and rightly so, with respect - in submissions that the provisions of the Assessment Act are complex. That they certainly are. It must be very difficult indeed for the Child Support Registrar (Registrar), who has day-to-day administration of the Act, to administer that Act. It must be even more difficult for those Australians who have, for one reason or another, occasion to look to and be subject to that Act to understand the nature and extent of their liabilities.

[5] Our society is governed by the rule of law, but such governance is put in jeopardy when legislation becomes so complex as not readily to admit of administration by ordinary, good, honest civil servants or ready comprehension of ordinary Australians of average intelligence. This particular appeal truly gives one pause for thought about whether we have, in any meaningful way, progressed or, rather, regressed, when one compares the Assessment Act with the drafting style that once commended itself to what the Constitution terms the Queen's Ministers of State for the Commonwealth, and, in turn, given Ministerial responsibility, to Parliament. There must come a time, surely, when Ministers of State discharging their duty, or, if they do not, Parliament, reject out of hand drafting of the present kind that is presented to them by those in public administration for approval.

1. Under the scheme for determining percentages of care for use in the administrative assessment of child support, existing care determinations continue in effect until such time as they are revoked. The circumstances in which an existing care determination may be revoked are restricted to those set out in Division 4, Subdivision C of the Assessment Act.
2. Relevantly to the circumstances of this case[7], section 54F of the Assessment Act provides for revocation of a determination of a percentage of care if (among other requirements):
   • the Registrar or Secretary is notified, or otherwise becomes aware, that the care of the child that is actually taking place does not correspond with the person's existing percentage of care; and

• the Registrar is satisfied that the person's cost percentage for the child would change if the Registrar were to determine another percentage to be the person's percentage of care for the child. If a new percentage of care (under the applicable provisions) were to be determined, it would not be the same as the existing percentage of care.

1. When Mr LTWS notified the Child Support Registrar of a change to the care arrangements on 17 April 2019, the existing percentage of care determination then in effect was 72% care to Ms DQFY and 28% care to Mr LTWS. It is by reference to that existing percentage of care that the first step of the test in section 54F of the Assessment Act is to be applied: that is, whether the care of the child that is actually taking place does not correspond with the responsible person's existing percentage of care for the child: paragraph 54F(1)(a) of the Assessment Act.
2. Section 54F of the Assessment Act will then require the revocation of the existing care percentage determination if a new care percentage determination determined under section 49 or 50 of the Assessment Act would change a person's 'cost percentage': paragraph 54F(1)(b) of the Assessment Act.
3. The reference to 'cost percentage' is a reference to a component of the administrative formula for calculating child support, that in turn corresponds to the care percentage, albeit in increments. It is provided for by section 55C of the Assessment Act. For example, where a person's care percentage is more than 14% but less than 35%, the cost percentage will be 24%. The change Mr LTWS notified the Child Support Registrar of on 17 April 2019, if established, would change his care percentage from 28% to 38%. Crossing the 35% care percentage threshold would mean, under section 55C of the Assessment Act, that the cost percentage would change from 24% to 25% plus 2% for each percentage point over 35% - so a 31% cost percentage.
4. Therefore, if it were to be established that the care that was actually taking place from 31 January 2019 was what Mr LTWS said it was, then section 54F of the Assessment Act would require that the existing care percentage determination be revoked.
5. Subsection 54F(3) of the Assessment Act would then regulate from what date the existing care percentage would be revoked. If the Child Support Registrar had been informed within 28 days of the change of care day, then the revocation would take effect for both parents from the day before the change of care day. If the Child Support Registrar were informed of the change more than 28 days after the change of care day, then the existing care percentage determination would be revoked from different days for each parent, with the parent with a reduction in care being impacted from the day care reduced, and the parent with increased care being benefited only from the day the Child Support Registrar was informed of the change.
6. Relevantly, section 50 of the Assessment Act then provides that if a care percentage determination is revoked under section 54F of the Assessment Act,[8] it is necessary to determine the person's percentage of care for the child during the care period, and it must correspond with the actual care of the child the person has or is likely to have during the care period. That determination will take effect from the day after the previous care determination was revoked in respect of each parent: section 54B(2)(c)(ii) of the Assessment Act.

1. Given the scheme, a clearly expressed legislative basis for bringing into existence multiple care percentages for different periods of time as part of a single care percentage determination process is elusive. However, in DQFY, as mentioned above, the Court dismissed the Child Support Registrar's appeal raising questions of law directed at the approach of the tribunal in that matter which the Child Support Registrar had understood to have done precisely that. The Court in DQFY found that the Tribunal did not exceed its jurisdiction in pronouncing a second care percentage determination,[9] because the Tribunal in that matter had not in fact (according to the Court) made two separate determinations,[10] but had made a single bifurcated determination in circumstances where 'the bifurcation of the replacement determination ... was necessitated by the uncontested evidence presented to the Tribunal that the parents had reached a parenting arrangement which would take effect from [a different and later date].'
2. In initial written submissions, the Child Support Registrar submitted, in relation to Mr LTWS and Ms CNTQ's case, that the AAT had jurisdiction to review the objection decision, but the objection decision was confined to answering the same question that presented itself to the objections officer. That question was whether to disallow or allow Mr LTWS' objection to the original decision that found that a change in care for the children occurred on 31 January 2019, and that the AAT was incorrect to then purport to determine that care of the children also changed on 12 October 2020, as that change had not been the subject of an objection decision or an original decision and was beyond the bounds of the AAT's limited jurisdiction of review.
3. It is necessary to emphasise that the Tribunal, as part of the executive government and as an administrative decision maker, is bound to diligently apply the ratio (at least) from binding judicial decisions, and DQFY is a decision where any expressed interpretation of the legislation or expression of legal principle will bind the Tribunal.
4. The Child Support Registrar submitted that the approach in DQFY may be distinguished and should not be followed in this case. The circumstances said to distinguish DQFY were said to be that in DQFY new facts emerged that were not before the Child Support Registrar when either the original or objection decisions were made, contrary to Mr LTWS and Ms CNTQ's case where the objection officer was aware that care had subsequently changed. It was said that in DQFY the evidence was uncontested, whereas in Mr LTWS and Ms CNTQ's case the parents had different positions as to when the subsequent care change took place.[11] The Child Support Registrar also pointed out that adopting the approach in DQFY would be inconsistent with the intended operation of the date of effect provisions in the child support legislation.
5. I invited the Child Support Registrar to provide further written submissions to identify the ratio (the reason for deciding) which binds me in DQFY, where I had indicated that I had difficulty putting my finger on the ratio of the decision as expressed in the reasons, given the result in dismissing the Registrars appeal on questions of law as those questions had been expressed. I queried whether paragraph [96] of the reasons in DQFY perhaps amounted to a binding ratio[12], and if so I observed that the parents have now put forward a common position in relation to when care of the children changed, and so in that regard the facts were similar. I also indicated I had difficulty identifying from the judgment in DQFY the various matters said to distinguish DQFY from Mr LTWS and Ms CNTQ's case in the Child Support Registrars initial written submissions.
6. In further written submissions, the Child Support Registrar elaborated upon his position regarding the impact of the judgment of Farrell J in DQFY. In those submissions, the Registrar noted that the first three grounds supporting the appeal were dealt with by the Court construing what the Tribunal had found in that matter contrary to the Registrar's understanding as to what the Tribunal had found. In this way the Court had determined the first three grounds as factual questions and not on any principle of statutory construction.
7. I accept that to be the case, and therefore need not set out in any further detail the background to DQFY or the Court's treatment of the first three grounds.
8. The fourth ground dealt with in DQFY is the ground which has caused me the most concern in ensuring I deal with this review in accordance with the legislation, within the limits of my jurisdiction, but also recognising that I am bound by any applicable reasoning of the Court in DQFY. The ground reflected the question of law as to whether the Tribunal (in DQFY) had exceeded its jurisdiction or powers on review in making the second care percentage determination.
9. In arguing before the Court that the Tribunal in DQFY had erred in that regard, the Registrar had argued that the Tribunal's power to make a determination of a responsible person's percentage of care for a child during a care period under subsection 50(2) of the Assessment Act is enlivened only if it revokes an earlier determination under that section. The Tribunal in DQFY had no power to receive the 'notification' required to revoke an existing determination (as required for example by paragraph 54F(1)(a) of the Assessment Act), and so in purporting to revoke a determination where a change had not been notified to the Registrar, and therefore not the subject of any earlier decision making process, the Tribunal had erred in law.[13]
10. The Court however did not accept that the Tribunal had made two separate determinations, on a factual basis. The Court found that a single replacement determination had been made related to two time periods having regard to the evidence before the Tribunal.
11. The Court found, contrary to the Registrar's construction of the facts in that case, that what the Registrar had contended was a notification the Tribunal had no jurisdiction to receive in order to revoke the care determination was not a notification, but was evidence directed towards other aspects of section 54F of the Assessment Act (specifically whether the cost percentage would change and whether a new determination of percentage of care would be different to the existing percentage of care).
12. Returning to the application of DQFY to this matter therefore, the Registrar submits that the Court did not address the assertion that the Tribunal did not have jurisdiction to make the second care percentage determination because on the facts as ultimately construed by the Court (which were different to how they had been construed in the Registrar's questions of law) and the issue did not arise for determination.
13. The Registrar submits that the statements of Farrell J at [96], being the aspect of the Court's judgment that I identified in the hearing as potentially expressing binding principle was merely an observation as to why in that case the care percentages determined could not go beyond a certain date.
14. The Registrar submits that the Court's reasons at [96] to [97] do not have any broader application, and that Farrell J did not lay down any legal rules or articulate any legal test, but merely rejected the Registrar's submissions 'at a factual level'.
15. Mr LTWS also provided further written submissions in response to those of the Registrar. Mr LTWS submits that DQFY permits the making of a 'bifurcated' replacement determination. As to the Registrar's contention that the change of care of October 2020 had to be the subject of a separate notification, Mr LTWS acknowledged that the reasoning of the Child Support Registrar was generally sound, but it was not plenary in its application to all child support case. It was submitted that in relatively few cases there will be a reason why a notification has not been made but that does not suspend that actual fact of a care change. Mr LTWS observes that the strict enforcing of the need to make a notification can result in a parent paying too much child support and also meeting additional costs in actually providing care, also identifying impacts on eligibility to family assistance. Mr LTWS submits that DQFY allows consideration of the change of care on 12 October 2020, and by inference therefore would avoid that perceived injustice. Mr LTWS in his submissions goes on to point out the fundamental purposes and design of the child support scheme in this regard.
16. After careful analysis of the decision in DQFY I have concluded that the Child Support Registrar's central submission that DQFY did not lay down any legal rules or articulate any legal test that binds me should be accepted. I consider that if such a legal rule or legal test had been laid down in DQFY that explains how and in what circumstances the legislative scheme provides for the pronouncement of a different care percentage to apply to the calculation of a child support liability without first revoking the previous care percentage determination I would be able to summarise and also articulate that principle, but I am unable to do so. Similarly, if DQFY had laid down a legal rule or legal test that explains how the process of administrative decision making leading to the revocation of a care percentage determination may commence for the first time in the Tribunal without first being the subject of a reviewable decision by the Registrar then I would be able to summarise and articulate that principle, but I am unable to do so. I accept the Registrar's submissions that DQFY proceeded on a factual basis, and no binding legal test or legal rule was pronounced.
17. It follows therefore that in my view it is necessary to revoke an extant care percentage determination before bringing a different care percentage determination into effect. I note that this understanding of the scheme of the Assessment Act is consistent with a notation endorsed upon orders made by consent by Kenny J in LJSS v KBNY and Child Support Registrar (9 June 2023)[14] in granting an extension of time, allowing an appeal and setting aside a decision of the AAT. In the notation, the Court noted by consent that:

"the Administrative Appeals Tribunal (General Division) made an error of law in its decision dated 23 May 2022 in finding that the second and third care determinations under subsection 50(2) of the Child Support (Assessment) Act 1989 (Cth) (Act) could be made without first revoking (either expressly or impliedly) the first and second determinations under section 54F or section 54H of the Act, pursuant to paragraph 50(1)(b) of the Act."

1. In my view, this feature of the scheme is plenary in its application, because it arises from the legislative text. Discipline is therefore required by decision makers to approach matters such as these in accordance with the statutory scheme, notwithstanding the complexity of its concepts, and that the application of those complex concepts often must take place in the context of incomplete evidence as to the facts and, on occasion, high conflict and the parties' profound dissatisfaction with the circumstances they find themselves in.
2. Having regard to the legislative scheme, I consider that each such occasion where an extant care percentage determination is revoked and replaced with another is an administrative decision which requires the Child Support Registrar to be notified or otherwise become aware that the care of a child is no longer taking place in accordance with that extant care percentage determination.
3. As submitted by the Child Support Registrar, the Tribunal is not a primary decision maker and it can only review decisions that have already been made. This proposition is a well-established one: Re Brian Lawlor Automotive Pty Ltd v Collector of Customs (NSW) (1978) 1 ALD 167 at 175. In this case, the AAT had jurisdiction to review the objection decision pursuant to section 89 of the Registration and Collection Act, and that objection encompassed only the decision arising out of Mr LTWS' notification of a change to the care arrangements on 17 April 2019.
4. In my view, the administrative controversy before this Tribunal is a review of the decision arising from Mr LTWS' notification of 17 April 2019, being the subject of an objection which was disallowed by an objections officer on 14 July 2023.
5. The (now) agreed events of 12 October 2020 are, in this case, legally immaterial to the question of whether Mr LTWS' notification of 17 April 2019 should have resulted in the revocation of the extant care percentage determination and its replacement with another, and are legally immaterial to whether his objection of 29 March 2023 to that decision should have been allowed or disallowed.
6. In viewing the events of 12 October 2020 as 'legally immaterial' to the decision under review, I must explain further exactly what I mean, by reference to the authority in Child Support Registrar v BKCZ [2023] FCA 1109. In that matter, the Court held that that the Tribunal must have regard to the material before it and is obliged to adopt an approach incorporating a consideration of events occurring after the date of notification of the change. The Court rejected what had been described as the 'point in time' approach, describing that approach as one in which the Tribunal considered itself obliged to disregard evidence of events arising after the date of notification.[15] The Court found nothing in the language used [in the relevant provision] that suggests any requirement on the decision maker to consider the matter at a time earlier than the date of the decision-making.
7. However, the Court in that matter pronounced those principles by reference to taking into account evidence of actual care during the care period_[16]_, recognising that by the time of a review, particularly at second review, the most reliable information which will assist in undertaking the task..."is information which is based upon actuals rather than what might be likely." [17]
8. The Court summarised the operation of the relevant provisions of the Assessment Act in this regard, recognising that the legislative scheme requires the identification of a person's percentage of care for the care period.[18]
9. To avoid doubt, I am bound to apply BKZC, and I am not applying the impugned 'point in time approach' as that approach was summarised in that decision. BKZC does not purport to be authority for the Tribunal making multiple care percentage determinations or primary decisions revoking care determinations, but rather affirms the principle that the Tribunal must take into account evidence of events even if they have occurred after the date of notification.
10. While the events of 12 October 2020 have indeed occurred after the date of notification, the events do not inform on the pattern of care during the care period pertaining to the change notified. Indeed the application of BKZC to the circumstances of Mr LTWS and Ms CNTQ's matter is in my acceptance, on their evidence in these proceedings, that the pattern of care notified by Mr LTWS on 17 April 2019 did in fact take place (as a matter of historical fact) during the balance of the care period I have identified. The events of 12 October 2020 are immaterial in the sense that they do not inform about the actual pattern of care that historically did in fact take place (now the period is well past) during the care period with which I am concerned.
11. In my disposition of this matter, I have found that from 31 January 2019 the care that was actually taking place of the children did not correspond with the existing care percentage determination that was then in place. This finding satisfies the requirements of paragraph 54(1)(a) of the Assessment Act.
12. I have further found that if a new care percentage determination was made, the cost percentage would change for each parent. This finding satisfies the requirements of paragraph 54(1)(b) of the Assessment Act.
13. Further to that finding, and applicable also to the next stage of the application of the statutory scheme, I have found that a new care percentage determination would be 62% in Ms CNTQ's care and 38% in Mr LTWS' care. My finding in this regard arises from the agreement of the parties, but for completeness I note that the agreement reflects the terms of a court order of 22 January 2019 which is now before me (Exhibit F). The terms of the court order permit the identification of a care period of 12 months commencing 31 January 2019 for the purpose of identifying the care that each parent will have or is likely to have. I consider the care period is therefore from 31 January 2019 to 30 January 2020.
14. The Child Support Registrar submits that any care period I identify cannot extend beyond 13 March 2023 when a subsequent care percentage decision was made. I do not expressly accept or reject that submission but the care period I have identified does not, in any event, purport to extend beyond that date.
15. It should be noted, for completeness, that the agreed change of 12 October 2020 that forms part of the evidence in this matter does not impact on the care period, and therefore does not materially relate to the identification of a care percentage that reflects the care that was had or that was likely to have been had during that care period.
16. With the provisions of subsection 54F(1) and (2) of the Assessment Act therefore relevantly satisfied, the care percentage determination must be revoked. The date of effect of that revocation is regulated for each parent by subsection 54F(3) of the Assessment Act.
17. It was not in dispute that the care actually changed on 31 January 2019 or that the Registrar was first made aware of the change on 17 April 2019. As the Registrar was not made aware of the change within 28 days of the 'change of care day', the provisions of paragraph 54F(3)(b) of the Assessment Act must be applied. As Mr LTWS' care percentage is to increase, the care percentage determination to be revoked is revoked from the day before the Registrar was made aware: 16 April 2019. As Ms CNTQ's care percentage determination was to decrease, the revocation in respect of her was to take effect from the day before the change of care day: 30 January 2019.
18. For completeness, given part of the hearing before the Tribunal was concerned with the circumstances of the delay in Mr LTWS objecting, the application of section 87AA of the Registration and Collection Act and the availability of a limited discretion as to the date of effect of a favourable (to Mr LTWS) objection outcome, it should be noted that the date of effect of the revocation under section 54F of the Assessment Act contains no equivalent discretionary considerations.
19. With the extant care percentage determination revoked, new care percentage determinations must be made. The rationale set out in paragraph 62 applies to that process, which in this case takes place pursuant to section 50 of the Assessment Act. The new care percentage determinations take effect in respect of Mr LTWS on 17 April 2019 and in respect of Ms CNTQ on 31 January 2019., being the day after the previous care percentage determination was revoked in respect of each of them.
20. This completes the care percentage determination decision process that is before the Tribunal. As explained above, the events of 12 October 2020, albeit now agreed, do not form part of that process and cannot be reflected in this Tribunal's decision at law. My review of the decision before me accords with the decision of the objections officer on Mr LTWS' objection and, with the exception of then moving on to address the events of 12 October 2020, also accord with the findings of the AAT.
21. I consider I must restrict the review outcome to the objection decision, and this requires me to set aside the decision of the Administrative Appeals Tribunal, and to substitute it with a decision affirming the objection officer's decision disallowing Mr LTWS' objection.
22. In this way, the matter Mr LTWS asked the Tribunal to address, namely the application of the discretion in section 87AA of the Registration and Collection Act does not, at law, arise. It arises only where an objection is allowed and some account must be taken of any delay in lodging the objection in the first place. As my decision effectively restores the decision to disallow the objection, section 87AA of the Registration and Collection Act has no application.

The decision of the Administrative Appeals Tribunal of 15 January 2024 is set aside and substituted with a decision affirming the decision to disallow Mr LTWS' objection.

I certify that the preceding seventy-one (71) paragraphs are a true copy of the reasons for the decision herein of Senior Member M Kennedy

............................[SGND]...................................

[3] T227. Note that contemporaneously with the objection process commenced by Mr LTWS, Ms CNTQ notified Services Australia on 27 March 2023 (T222) of a change of care to 50% care for each parent from 14 March 2023. That care change was accepted on 29 March 2023 with effect from 14 March 2023.

[7] Revocation is also provided for by sections 54G and 54H of the Assessment Act. Without reproducing that legislation, as explained by the Court in Child Support Registrar v BKZC [2023] 1109 at [101], it is necessary to consider first, the position under section 54G, and if section 54G does not apply, the position under section 54F, and only if section 54F does not apply the position under section 54H. As both parents have at least regular care (that is, at least 14% care) at all material times, section 54G will not apply.

[11] or at least they did until the matter was dealt with by the AAT, and as mentioned above, the parents did not have different positions before me.

[12] Namely, that "The bifurcation of the replacement determination ... was necessitated by the uncontested evidence presented to the Tribunal that the parents had reached a parenting arrangement which would take effect from [a different and later date].' (my emphasis).

[13] The Registrar had also developed an argument to the affect that the Tribunal had purported to make a determination in respect of a period that was different to the care period it had identified in its reasons. This was rejected on a factual basis by the Court.