What is the National Insurance number?

A National Insurance number (NINo) is a unique personal reference number used by HM Revenue and Customs and the Department for Work and Pensions to track an individual's National Insurance contributions, tax payments, and entitlement to state benefits and the state pension.

The format is two letters, six digits, and a final letter, for example QQ 12 34 56 A. It is issued to each person and kept for life. Most British residents receive their number automatically shortly before their 16th birthday. Anyone who has moved to the United Kingdom and has the right to work must apply for a number through the government's online service at gov.uk. Applicants need to prove their identity and their right to work or claim benefits. A number is normally issued within eight weeks of a successful application.

National Insurance itself is a set of compulsory contributions paid by most workers and their employers. Contributions are deducted from wages through Pay As You Earn (PAYE) for employees, paid through Self Assessment by self-employed workers, and credited automatically in certain circumstances such as while claiming Jobseeker's Allowance, carer's benefits, or statutory maternity, paternity, or adoption pay. Contributions fund the state pension, the contribution-based elements of Jobseeker's Allowance and Employment and Support Allowance, Maternity Allowance, and bereavement benefits, as well as contributing to the NHS.

Contribution classes depend on how someone earns money. Employees pay Class 1 contributions above the primary threshold. Employers pay Class 1 secondary contributions on top. Self-employed people pay Class 2 (a flat weekly rate, for those earning above a threshold) and Class 4 (a percentage of profits between set limits). Voluntary Class 3 contributions can be paid to fill gaps in a record, which can be important for state pension entitlement.

Eligibility for most contribution-based benefits depends on how many "qualifying years" of contributions or credits a person has. The full new state pension, for example, generally requires 35 qualifying years, and a minimum of around 10 qualifying years is usually needed to receive any new state pension at all.

The National Insurance number is needed by an employer to operate PAYE correctly, by a bank for tax purposes on savings interest, by HMRC for Self Assessment, and by the DWP for any claim to means-tested or contributory benefits. It is also used by student finance bodies, HM Land Registry for certain transactions, and pension providers.

The number itself is not proof of identity or of the right to work. Those must be evidenced separately, for example with a passport, visa, or biometric residence permit.