61 Secondly, the defendants submit that because they had already paid amounts exceeding the amount payable under the Subcontract, the moneys the subject of the Determination cannot be paid by RLJV 'on account of' the total amount payable, as is contemplated by the statutory scheme. I accept that the statutory scheme is for payment pursuant to a determination to be made on account: s 40. However, whether the amount payable under the Subcontract, as varied and performed, has or has not been exceeded, is a matter evidently in issue between the parties. It is one of the substantive matters which will be required to be determined in any ultimate proceedings between the parties (if the parties are not able to resolve the dispute themselves). Thus, the amount correctly due under the Subcontract is a matter yet to be determined. Until that occurs, payment pursuant to the Determination would, consistently with s 40, be an advance towards the total amount payable. If, as RLJV contends, the amount paid is found to exceed the total amount properly payable, then orders will be made under s 45(4) for the repayment or restitution of the amount so paid.