National Insurance Number — What It Is and How to Apply
National Insurance Number — What It Is and How to Apply
What a National Insurance number is, why you need it, and how to get one.
Last reviewed: May 2026
What this is
A plain-English guide to the UK National Insurance (NI) number — what it is, who needs one, and the application process.
Why it matters
Your National Insurance number is your unique personal reference number for tax and National Insurance contributions in the UK. You legally need it to work — employers use it to make sure the correct tax and National Insurance is deducted from your wages. Without one, you could be taxed incorrectly or miss out on state pension contributions.
What to prepare
- •Proof of the right to work in the UK (passport with vignette and UKVI online account / eVisa)
- •Proof of address
- •Proof of student status
Steps to take
- 1If you have a pre-existing NI number from a previous UK stay, note it — you do not need to reapply.
- 2If you do not: call the DWP NI number helpline on 0300 200 3500.
- 3DWP will schedule an evidence interview — bring your passport and UKVI online account or eVisa.
- 4Your NI number will be posted to you within 3–4 weeks.
- 5Save your NI number securely — you will need it for every job and for your tax returns.
Common mistakes to avoid
- ✗Starting work without an NI number — you can start work before receiving it but must apply promptly.
- ✗Losing the letter — NI numbers are posted once. If lost, you must request a replacement from HMRC.
Official sources
HMRC NI number: gov.uk/apply-national-insurance-number | DWP: dwp.gov.uk
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Disclaimer
Beginly provides general guidance on National Insurance. For tax advice, contact HMRC or a qualified accountant.