(4) In subsection (5) —
- (a) for the word "contributions", in the first place where it occurs, there shall be substituted the words "earnings or Class 2 or Class 3 contributions;
- (b) paragraph (a) shall be omitted; and
- (c) for the words from "shall be derived" to the end of the subsection there shall be substituted the words "may be derived—
- (i). from earnings upon which Class 1 contributions have been paid;
- (ii). from earnings which have been credited;
- (iii). from contributions in different classes paid or credited in the same tax year;
- (iv). by any combination of the methods mentioned in paragraphs (i) to (iii) above."