“prescribed rate” in relation to any interest payable in terms of this Act, means for the purposes of –

(a)     interest payable to any taxpayer under the provisions of section 89quat(4), a rate determined at four percentage points below the rate contemplated in paragraph (b); or

(b)     any other provision of this Act, such rate as the Minister may from time to time fix by notice in the Gazette in terms of section 80(1)(b) of the Public Finance Management Act, 1999 (Act No. 1 of 1999): Provided that where the Minister fixes a new rate in terms of that Act, that new rate applies for purposes of this Act from the first day of the second month following the date on which that new rate came into operation;