What a National Insurance number is used for
Your National Insurance number links your tax, National Insurance contribution and certain benefit records to you. GOV.UK says it remains the same throughout your life, including if you change your name, address or employment.
Employers, HM Revenue and Customs (HMRC), the Department for Work and Pensions (DWP) and authorised pension or benefit providers may need it. It is not proof of identity or proof that you have permission to work in the UK.
According to GOV.UK, the usual format contains two letters, six numbers and a final letter, such as QQ123456C. That example is illustrative and must not be used as a real number.
Fraud warning: Treat your National Insurance number as sensitive personal information. Do not publish it online or give it to an unexpected caller, texter or email sender claiming to represent HMRC or DWP.
How to find a lost National Insurance number
Start with records you already control. GOV.UK says your number may appear in your personal tax account, the HMRC app, payslips, a P60, benefit letters or correspondence about tax, pensions and National Insurance.
| Method | What to do | Important point |
|---|---|---|
| Personal tax account | Sign in through GOV.UK and open your National Insurance details. | Use GOV.UK directly rather than a link in an unsolicited message. |
| HMRC app | Sign in and view your personal details. | Download the official HMRC app only from a recognised app store. |
| Employment records | Check payslips or your P60. | Your payroll team may already hold the number you supplied. |
| Official letters | Review tax, pension or benefit correspondence. | DWP and HMRC letters may display it. |
| HMRC confirmation | Use the GOV.UK service to request confirmation if you still cannot find it. | HMRC must verify your identity before releasing personal information. |
If the missing number is delaying a benefit check, review which support you may be entitled to while you recover it. A calculator can indicate possible eligibility, but DWP or your local authority makes the formal decision.
How to apply for your first National Insurance number
Apply only if you do not already have a National Insurance number. GOV.UK provides the official application service for people living in England, Scotland or Wales, while applicants in Northern Ireland should follow the process published by nidirect.
Before applying, check whether the number was issued previously, including on benefit or tax correspondence. GOV.UK warns that you should not apply for another number simply because you cannot find the original.
- Confirm your right to work position: a National Insurance number does not grant immigration status or permission to work.
- Gather identity information: the official service will explain which identity documents or evidence are accepted for your circumstances.
- Use the correct government channel: begin at GOV.UK in Great Britain or nidirect in Northern Ireland.
- Respond to identity checks: provide only the evidence requested through the official process.
GOV.UK says you can start work before receiving your National Insurance number if you can prove your right to work in the UK. Give the number to your employer once it has been issued so payroll records can be updated.
Practical tip: Keep copies of documents you submit and note any official application reference. Never pay an unofficial website to complete a government application that you can make through the official route.
National Insurance numbers and benefit claims
DWP may ask for your National Insurance number to match you with an existing benefit record and verify aspects of a claim. If you cannot find it, do not guess: tell the relevant office and follow its identity-checking instructions.
For Universal Credit, use the official claim service and provide accurate identity, income, housing and household information. SupportFund's Universal Credit guidance can help you prepare, but it does not replace a DWP claim or decision.
A National Insurance number by itself does not establish benefit entitlement. Eligibility can depend on factors such as income, savings, health, caring responsibilities, housing costs and immigration status, depending on the scheme.
If you need help before a claim is resolved, check emergency household support options. Local authority assistance varies by area, so confirm availability and eligibility directly with your council.
Correcting details and avoiding scams
You normally keep the same National Insurance number for life. If your personal details change, use the relevant GOV.UK service to tell HMRC rather than trying to obtain a replacement number.
- Name or address changes: update HMRC through your personal tax account or the official contact route.
- Incorrect employer record: ask payroll to check the number against your official record.
- Possible misuse: contact HMRC through contact details published on GOV.UK and review your personal tax account for unfamiliar information.
- Suspicious message: do not disclose the number, click links or transfer money because of an unexpected threat.
HMRC publishes guidance on recognising and reporting suspicious emails, texts, phone calls and online messages. HMRC does not use threatening contact to demand that you reveal sensitive information or make an immediate transfer to avoid arrest.
Before acting: type GOV.UK into your browser yourself and locate the relevant HMRC service. Do not rely on a telephone number or web address supplied in an unsolicited message.
Benefit and tax rules can change. Confirm current rates, thresholds and procedures on GOV.UK before making a financial decision or submitting a claim.