If you've lived or worked in the UK, you probably already have a National Insurance number, even if you don't know it. Check a payslip, your P60 or a letter about tax, pensions or benefits, or look in the HMRC app or your personal tax account. HMRC can't give you your number over the phone or on webchat, so those are the routes. If you've never had one, you can apply online once you're in the UK.
Your number stays the same for life, even if your name or address changes. It's made up of 2 letters, 6 numbers and a final letter, like QQ123456B.
Where to find your National Insurance number
| Where to look | Good to know |
|---|---|
| Payslip or P60 | Tax-related documents carry your number |
| Letters about tax, pensions or benefits | Worth checking old paperwork first |
| HMRC app | If you live in the UK; you can also download a letter showing your number |
| Personal tax account | If you already have one; same letter download option |
| Apple or Google Wallet | Only if you've saved it there before |
| Back of your BRP, or your UKVI account | If you have a biometric residence permit or eVisa |
Most UK teenagers get a letter with their number shortly before their 16th birthday. That happens automatically when a parent or guardian filled in a Child Benefit claim form for them, and it goes to the address HMRC has on file.
If you can't find it anywhere
GOV.UK has a short question tool that tells you the best way to find your number for your situation. It times out after 15 minutes of inactivity and doesn't save your answers, so have your details ready.
If the online routes don't work, you can ask for your number by post with form CA5403:
- Fill in the form online.
- Print it and sign the declaration.
- Include any documents to confirm your identity.
- Post it to HMRC at the address on the form page.
Don't bother calling. HMRC says it can't give you your National Insurance number over the phone or on webchat, which is also why any caller offering to tell you yours should ring alarm bells.
How to apply for a National Insurance number
You can apply if you live in the UK, have the right to work here, and are working, looking for work or have an offer to start. You can only apply while you're in the UK. If you've had a number before, don't apply again: it doesn't change when your details do.
After you've proved your identity, it can take up to 4 weeks to get your number. Call the application helpline if you applied more than 4 weeks ago, you've moved house since applying, or your personal details have changed. Have the application reference number from your confirmation email ready.
The good news if you've just arrived: you can start work before your number comes through, as long as you can prove your right to work in the UK.
Starting a new job
GOV.UK's start a new job checklist puts getting your National Insurance number as step 1, because you'll usually need it when you start. Before your first day, your new employer will also ask for proof of your identity, details of any benefits you get, and your P45. If you don't have a P45, you fill in the starter checklist instead, which gives your employer the details they need to set up your tax correctly from the start.
When you don't need one
- To start an application for benefits or a student loan. You'll be contacted if a number's needed.
- To apply to the EU Settlement Scheme.
- If you already have one, even after a name change or a move.
Who can ask for your number
GOV.UK's advice is to share your National Insurance number only with people who need it, to prevent identity fraud. The list includes HMRC, your employer, DWP if you claim benefits, your local council for Housing Benefit, Electoral Registration Officers, the Student Loans Company, your pension provider and your ISA provider.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
Here's the one that surprises online traders and creators: websites or apps you trade goods or services through can ask for your number if they're required to report to HMRC. So if a platform you trade on asks for it, that can be legitimate, as long as you're on the platform itself and not answering an email link.
The flip side is that fake recruiters and job ads ask for it too. Our guide to spotting fake remote job listings in the UK covers the red flags, and being asked for your number before you've even had an offer is worth pausing on.
If you're self-employed
Your National Insurance number stays the same for life, whether you're employed, self-employed or both, so there's no separate number to get for your business. If you're starting a business in the UK, find your number before you start registering for anything, so you're not hunting for it halfway through a form.
My advice
Download the HMRC app and save your number to your phone's wallet now, so you're never hunting for an old P60 again. Then treat the number like a password: give it to your employer, HMRC and the services on GOV.UK's list, and nobody who contacts you out of the blue.
Frequently asked questions
How can I find my National Insurance number?
Check a payslip, P60 or letters about tax, pensions or benefits. You can also find it in the HMRC app, your personal tax account, or your Apple or Google Wallet if you saved it there.
Can HMRC tell me my National Insurance number over the phone?
No. HMRC can't give you your National Insurance number over the phone or on webchat. Use the HMRC app, your personal tax account, or form CA5403 to get it by post.
How long does it take to get a National Insurance number?
It can take up to 4 weeks to get your National Insurance number after you've proved your identity. You can start work before then if you can prove your right to work in the UK.
Does my National Insurance number change if I change my name?
No. Your National Insurance number stays the same for life, even if your personal details change, so you don't need to apply for a new one.
What does a National Insurance number look like?
It's made up of 2 letters, 6 numbers and a final letter, for example QQ123456B.
