Compound interest on certain sums
J7. Compound interest under regulations J2(3)(e)(iii) and J6(1)(d)(ii) and Parts I paragraph 1(2)) and V of Schedule 16 is to be calculated—
(a)at the rate of 6 per cent with yearly rests for each complete period of a year ending before 1st April 1977 (and any residual period of less than a year is to be ignored), and
(b)at the rate of 21 per cent with 3-monthly rests for each complete period of 3 months beginning after 31st March 1977 (and any residual period of less than 3 months is to be ignored).