Taxation (Interest on Overpayments and Early Payments) Act 1983 PART IIIAA - DELAYED REFUND INTEREST ON RUNNING BALANCE ACCOUNT (RBA) SURPLUSES View history reference View history note Hide history note History Part IIIAA inserted by No 179 of 1999. SECTION 12AD 12AD PERIOD OF INTEREST FOR RBA SURPLUSES View history reference Interest under this Part is payable for the period from the end of the RBA interest day until the end of the day on which the refund takes place. View history note Hide history note History S 12AD inserted by No 179 of 1999.