National Insurance number
The National Insurance number is used as a reference number in the Pay As You Earn system, and also by the self-employed. It is also used in applications for Individual Savings Accounts (ISAs), to check that an individual has opened only one ISA in a tax year.
Social Security Contributions and Benefits Act 1992
The Social Security Contributions and Benefits Act 1992 (c 4) is the primary legislation concerning the state retirement provision, accident insurance, statutory sick pay and maternity pay in the United Kingdom.