Interest on delayed refunds: interest accrues when refunds remain unpaid after the prescribed period; higher rate for final-order refunds. If a refund ordered under the refund provision is not paid within the prescribed period, interest at a rate notified by the government on the council's recommendation accrues from the day after that period until payment; where the refund follows a final adjudicatory or appellate order a higher notified rate applies, and orders by appellate bodies are treated as orders under the operative refund provision for interest purposes.