A new employer’s form, a pension app or a student finance account has asked for your National Insurance number, and you’re left wondering, “what is my National Insurance number?” You almost certainly have one already, and it’s probably written on a document in your drawer or inbox. This guide explains what a National Insurance number looks like, the quickest places to find yours, what to do if you can’t, and how to keep it safe.
- Your number is unique to you and normally stays the same for life.
- Payslips, P60s and letters about tax, pensions or benefits usually show it.
- The HMRC app and your personal tax account let you view it and download a letter.
- If you can’t find it online, you can ask for it in writing using form CA5403.
- It isn’t proof of identity or proof that you can work in the UK.
What Is My National Insurance Number and What Does It Look Like?
Your National Insurance number is the reference the Government uses to record the National Insurance contributions you pay or are credited with. Those contributions build your entitlement to the State Pension and to some benefits. The same number also helps link your earnings and tax records, which is why employers, pension schemes and HMRC ask for it.
It is unique to you. You keep the same number when you change job, move house or change your name. As the charity Turn2us points out, it isn’t a form of identity in itself; it is simply your record number.
Why organisations ask for it
Employers need your number so the National Insurance they deduct from your pay is credited to your record. Pension schemes use it to claim tax relief and confirm contribution limits, ISA providers need it to report accounts to HMRC, and student finance uses it to match repayments to your earnings. Without it, records can end up incomplete or delayed.
The format
HMRC’s National Insurance Manual (NIM39110) sets out the rules for a genuine number:
| Part | Rule |
|---|---|
| Start | Two letters |
| Middle | Six digits |
| End | One letter, which is always A, B, C or D |
| Letters never used first or second | D, F, I, Q, U and V |
| Letter never used second | O |
| Prefixes never issued | BG, GB, KN, NK, NT, TN and ZZ |
HMRC uses QQ 12 34 56 A as its example. It is only an illustration and isn’t a real number, which is why you’ll never be issued a number starting with Q.
How to spot a typo
- Check you haven’t written the letter O where a zero belongs, or I instead of 1.
- Make sure there are exactly six digits in the middle.
- Check the final letter is there and is A, B, C or D.
- Spaces don’t matter; QQ123456A and QQ 12 34 56 A are the same.
Where to Find Your National Insurance Number
The quickest answer to “what is my National Insurance number?” is usually sitting in your own paperwork. GOV.UK’s guidance suggests checking the paperwork you already have before anything else. Most people find their number in one of these places:
| Document | Where to look | Notes |
|---|---|---|
| Payslip | Usually near your name, tax code and employee details | Your current or any recent employer’s payslip will do |
| P60 | Near the top, with your personal details | Your employer gives you one after each tax year ends |
| P45 | In the employee details section | Issued when you leave a job |
| Letters about tax | Often in the reference panel | Tax code notices and calculations from HMRC |
| Letters about benefits or pensions | Often next to your name or reference | From DWP or your pension provider |
| Pension statements | In your member details | Workplace and personal pensions usually record it |
| Student loan or student finance letters | In your account details | Check your online account too |
Reading your payslip
Payslip layouts vary between employers, but the number is normally in the box with your name, employee number and tax code. It may be labelled “NI number”, “NINO” or “National Insurance No.” Next to it you’ll often see a single letter called the NI category letter, which shows the rate of National Insurance you pay. That letter isn’t part of your number, so don’t add it on.
Find it online
- The HMRC app. If you live in the UK, you can view your number in the app.
- Your personal tax account. If you already have one, your number is shown there.
- Apple or Google Wallet. If you saved your number to your phone’s wallet, it will be there.
- A letter you can download. GOV.UK says you can use the app or your personal tax account to download a letter showing your number, which is useful if someone needs written confirmation.
- The GOV.UK guided tool. It asks a few questions and tells you where to look. It times out after 15 minutes of inactivity and doesn’t save your answers.
Signing in for the first time
The first time you use the HMRC app or your personal tax account, you’ll need to set up sign-in details and prove your identity. This usually means answering questions using information from documents such as a payslip, P60 or passport, or using photo ID. Once that’s done, you can see your number whenever you need it, together with your tax code and National Insurance record.
What Is My National Insurance Number? The Fastest Route for You
| Your situation | Quickest way to get your number |
|---|---|
| You’re employed now | Check a recent payslip or your last P60 |
| You’re self-employed | Sign in to your personal tax account or the HMRC app |
| You’re claiming benefits or a pension | Look at a recent DWP or pension letter |
| You’re about to turn 16 | Look for the letter HMRC normally sends shortly before your 16th birthday |
| You can’t get online and have no paperwork | Ask for your number in writing using form CA5403 |
| You moved to the UK and have never had one | You’ll need to apply instead; see below |
If you’re self-employed, you’ll often be asked for your Unique Taxpayer Reference too. Our guide on where to find your UTR number covers that separate reference.
If You Can’t Find It Online: Form CA5403
If your paperwork and the online routes don’t work, you can ask HMRC to send you your number by post using form CA5403, as explained on GOV.UK’s page about getting your number by post. The process is:
- Fill in form CA5403 online.
- Print it and sign the declaration.
- Include the documents GOV.UK asks for to confirm your identity.
- Post everything to the HMRC address shown on the GOV.UK page.
Use this route if you still can’t answer “what is my National Insurance number?” from your paperwork or account. GOV.UK doesn’t give a timescale for a reply, so if you need your number for a deadline, try the app or your personal tax account first. If you’ve never had a number at all, this form isn’t the right route; you need to apply instead.
Helping a family member find theirs
You can’t look up someone else’s National Insurance number for them, even a close relative. They can check their own payslips, P60 or HMRC letters, sign in to their own HMRC app or personal tax account, or complete and sign form CA5403 themselves. If they need help managing their tax affairs more generally, GOV.UK explains how someone can be given authority to act for them.
Can HMRC Tell Me My Number Over the Phone?
No. GOV.UK states clearly that HMRC can’t give you your National Insurance number over the phone or on webchat. That protects you, because it stops anyone who has your basic details from obtaining your number by pretending to be you.
If you contact HMRC about your number, expect to be pointed to the app, your personal tax account or the postal form. For other questions about your National Insurance record, HMRC’s contact details are on the GOV.UK National Insurance enquiries page.
Some websites charge to “find” or “recover” your National Insurance number. You don’t need to pay anyone: the GOV.UK routes above are free.
Changed your name or address?
Your number doesn’t change, but your details on HMRC’s records should be kept up to date so letters reach you. You can usually update your name or address through your personal tax account or the HMRC app. If HMRC writes to an old address, you could miss the letter confirming your number or details about your National Insurance record.
What Is My National Insurance Number If I’ve Never Had One?
If you grew up in the UK, you’ll usually have been sent a number shortly before your 16th birthday, so you probably have one even if you’ve never used it. If you moved to the UK from abroad, you may not have a number yet and may need to apply for one on GOV.UK. You must have the right to live and work in the UK to apply.
You don’t have to wait for the number before starting a job. According to LITRG’s guidance for employers, you can start work as long as you can prove your right to work, then give your employer the number once it arrives. Our sister site Eternity Accountants has a step-by-step guide on how to apply for a National Insurance number.
What a National Insurance Number Is Not
Answering “what is my National Insurance number?” also means being clear about what the number isn’t, because it is often confused with other references.
| It isn’t… | Why it matters |
|---|---|
| Proof of identity | Organisations that need to check who you are will ask for other documents |
| Proof of your right to work | Employers must carry out their own right-to-work checks, as LITRG explains |
| A UTR | Your Unique Taxpayer Reference is a separate 10-digit number used for Self Assessment |
| A TN number | A temporary number starting with TN isn’t a real National Insurance number, and HMRC doesn’t accept it |
| A TRN | A Temporary Reference Number lets someone pay tax or National Insurance, but NIM39110 says it isn’t a National Insurance number |
If your payslip shows a number starting with TN, or a mix of numbers and letters that doesn’t match the format above, your employer probably doesn’t have your real number. Find it using the routes in this guide and give it to them so your contributions are recorded properly.
Why getting it right matters for your State Pension
Your National Insurance record decides how much State Pension you’ll get. Under the new State Pension, you usually need 35 qualifying years for the full amount. If an employer uses the wrong number, or none at all, contributions may not reach your record. Once you know your number, check your National Insurance record in the HMRC app or your personal tax account and query any years that look incomplete.
Keeping Your Number Safe
Your number is personal information, so share it only where there’s a genuine need. That usually means your employer, HMRC, the Department for Work and Pensions, your pension provider, an ISA provider or the student loans service. Don’t post it on social media or send it to anyone who contacts you unexpectedly.
Be wary of any call, text or email that claims there’s a problem with your National Insurance number, asks you to confirm it, or demands payment. HMRC publishes examples of phishing and bogus contact, and you can report suspicious HMRC messages on GOV.UK. If in doubt, don’t reply; check your records through the HMRC app or your personal tax account instead.
Myths vs Facts
Some of the answers to “what is my National Insurance number?” you’ll find online are out of date or simply wrong. Here are the most common ones.
| Myth | Fact |
|---|---|
| A National Insurance number is nine digits long. | It has six digits between two letters and a final letter. |
| HMRC will read my number to me on the phone. | HMRC can’t give it out by phone or webchat. |
| I should have a plastic National Insurance card. | Plastic cards stopped being issued years ago, as the CIPP reported; numbers are now confirmed by letter. |
| My number changes when I marry or move. | It stays the same for life. |
| QQ 12 34 56 A is a real number. | It is HMRC’s example only. |
What Is My National Insurance Number? FAQs
What is my National Insurance number and how can I find it quickly?
Check a recent payslip or your P60. If you don’t have those, look in the HMRC app or your personal tax account, where you can also download a letter showing the number.
Is my National Insurance number on my P60?
Yes. Your P60 shows your National Insurance number alongside your other personal details.
Can HMRC tell me my number over the phone?
No. HMRC can’t give out your National Insurance number by phone or webchat. Use the app, your personal tax account or form CA5403 instead.
Does my National Insurance number ever change?
No. It stays the same throughout your life, including if you change your name or address.
Is a National Insurance number the same as a UTR?
No. A UTR is a separate 10-digit reference used for Self Assessment. You may need both.
What does a National Insurance number look like?
Two letters, six digits and a final letter that is A, B, C or D, such as HMRC’s example QQ 12 34 56 A.
What if I’ve never had a National Insurance number?
If you grew up in the UK, you were probably sent one before age 16. If you moved here from abroad, you may need to apply on GOV.UK.
How do I get a letter showing my National Insurance number?
Download one from the HMRC app or your personal tax account, or request one by post using form CA5403.
Final Verdict
If you’re asking “what is my National Insurance number?”, the answer is almost always already in your paperwork or your HMRC account. Start with a payslip or P60, then try the HMRC app or your personal tax account, and use form CA5403 only if those fail. Check the number matches the official format, give it only to organisations that genuinely need it, and ignore any unexpected message asking you to confirm it.
- Look at a recent payslip, P60 or HMRC letter.
- If you can’t find it, sign in to the HMRC app or your personal tax account.
- Save it somewhere secure, such as your phone’s wallet.
- Use form CA5403 only if the online routes don’t work.