NI Number (National Insurance Number)
UK tax glossary · Last reviewed: April 2026
Your National Insurance number (NI number or NINO) is a unique reference in the format two letters, six digits, one letter (e.g. QQ 12 34 56 A). It ensures your NI contributions and tax payments are recorded against your individual record.
You need your NI number when starting a job, applying for benefits, filing a Self Assessment return, and opening certain financial products. Your NI number does not change, even if your personal circumstances do.
You receive your NI number automatically at 16 if your parents registered you in the UK system, or you can apply for one via the Department for Work and Pensions. Never share your NI number unless necessary — it is a target for identity fraud.
Common questions
Where can I find my NI number if I have lost it?
Check an old payslip, P60, or any letter from HMRC or the DWP. You can also retrieve it through your Personal Tax Account at gov.uk or by calling HMRC's NI number helpline.
Can I start a job without an NI number?
Yes — you can legally work while waiting for an NI number. Your employer should still pay you and attempt to deduct the correct tax and NI. Notify your employer as soon as your number arrives.
Related resources
TaxHelper provides general information based on published HMRC rates and guidance. It is not regulated financial or tax advice. For decisions involving significant sums, complex circumstances, or if you are unsure, speak to a qualified accountant or HMRC directly.