NIM01006 - Class 1 structural overview: earnings brackets
Sections 8 and 9 of the Social Security Contributions and Benefits Act (SSCBA) 1992
From 6 April 2003, the structure of primary Class 1 NICs provides for two primary percentage rates, although a single secondary percentage rate was maintained. Guidance on these changes can be found at NIM01100 onwards.
Further changes to the structure of primary Class 1 NICs were introduced from 6 April 2009. Guidance on these changes can be found at NIM01200 onwards.