What Is My National Insurance Number? A National Insurance number (NI number) is a unique reference used in the UK to track your tax and National Insurance contributions. It ensures that everything you pay is recorded against your name only. Your NI number stays the same for life and follows a specific format:
Two letters
Six numbers
One final letter (e.g. QQ123456B)
It’s essential for working, paying tax, and accessing benefits in the UK. What Your NI Number Is Used For Your National Insurance number is used by organisations such as HM Revenue and Customs to:
Record your tax and National Insurance contributions
Track your eligibility for the State Pension and benefits
Identify you within the UK tax system
Employers will ask for it when you start a job so they can deduct the correct tax and contributions. How to Find Your National Insurance Number If you’re asking “what is my national insurance number”, you won’t be able to retrieve it directly here—but you can find it in several places:
On your payslip or P60
On letters about tax or benefits
In your personal tax account or HMRC app
On official documents sent to you around age 16
If you still can’t find it, you can request it online through HMRC, and they will send it to your registered address. Important Things to Know
Your NI number is unique to you and should not be shared unnecessarily
It is not proof of identity, even though it is widely used
You usually receive it automatically before your 16th birthday if you live in the UK
Summary A National Insurance number is a lifelong identifier used to track your tax and contributions in the UK. If you don’t know yours, the quickest way to find it is by checking official documents or logging into your HMRC account.
