regulations 2 and 3(c) of the Social Security (Contributions) (Amendment No. 3) Regulations (Northern Ireland) 199449;

the Social Security (Contributions) (Amendment No. 4) Regulations (Northern Ireland) 199550; and

regulations 2, 3(c) and (d) and 4(a) and (c) of the Social Security (Contributions) (Amendment No. 6) Regulations (Northern Ireland) 199651.