What is a National Insurance number and how do I get one?
A National Insurance number is the reference HMRC uses for your tax and National Insurance contributions. International students apply online once in the UK with a UK address; the number arrives by post within about four weeks, and you can start work while you wait.
Reviewed 17 September 2026 · 1 min read
Short answer: A National Insurance number is your reference for tax and benefits. Apply online on GOV.UK after you arrive; it takes up to four weeks. You can start work before it arrives.
Check whether you already have one
Some visa decision letters and eVisas show an NI number already allocated. If yours does, you do not need to apply.
How to apply
- Go to gov.uk/apply-national-insurance-number.
- Prove your identity: usually through the UK Immigration ID Check app with your passport, or by uploading documents and joining a short video call.
- Give a UK postal address. The number is sent by letter, usually within four weeks, sometimes eight in peak months.
Starting work first
Employers can pay you without the number; you give them the number when it arrives and HMRC matches the records. What they need on day one is your right-to-work share code, not the NI number.
Keep it private
The number is yours for life. Give it only to employers, HMRC and your bank. The AnyRoot app stores it in the UK essentials locker.
Sources
General information, not regulated immigration advice. Rules change; check the source before you act, and speak to an IAA-registered adviser about your case.