Take it one step at a time.
There is nothing to cancel
A National Insurance number is not an account you close, and no one expects you to cancel it. GOV.UK's own guidance says a person's number stays the same for life and is unique to them, and nothing published suggests that changes when they die. What actually happens is that HMRC and the Department for Work and Pensions are told about the death, and they then deal with the tax, benefits and entitlements recorded against that number. They write to you afterwards about anything owed or due.
Tell Us Once does the telling — in England, Wales and Scotland
One report at the register office reaches both departments. When you register the death, the registrar offers Tell Us Once, and GOV.UK puts the result plainly: HMRC and DWP will contact you about the tax, benefits and entitlements of the person who died. Tell Us Once covers England, Scotland and Wales. It isn't available in Northern Ireland — there, each department is contacted separately through Northern Ireland's own Bereavement Service, which asks for the National Insurance number, date of birth and date of death where you have them.
Without Tell Us Once, it is two phone calls
You can tell HMRC and DWP yourself, and it's two calls rather than a pile of forms. HMRC's bereavement and deceased estate line is 0300 322 9620, Monday to Friday, 8am to 6pm, closed on bank holidays — lines are quieter before 10am. If you'd rather write, the address is Bereavement Services, HM Revenue & Customs, BX9 2BS. The DWP Bereavement Service is 0800 151 2012, with 0800 731 0453 for Welsh and Relay UK on 18001 then 0800 151 2012, Monday to Friday, 8am to 6pm; that call cancels the person's benefits and entitlements, including the State Pension.
Where the number is written down
Most families find it on paper that's already in the house. GOV.UK lists a payslip, a P60, and letters about tax, pensions or benefits as the places a National Insurance number appears. In practice a P45 and any self-assessment or tax-return correspondence usually carry it as well. HMRC's online services are for the account holder — that is not a route to use on someone else's behalf.
If it truly cannot be found — the official route, honestly described
There is a published fallback, and there is a limit to what GOV.UK will tell you about it. Form P1000, which registers you with HMRC as the person dealing with the estate, asks for the National Insurance number — but HMRC's own guidance says that if the person did not have one, you should call the Bereavement Helpline instead of sending the form. That note covers someone who never had a number — GOV.UK does not publish what to do when a number exists but simply cannot be found. The helpline is still the right place to start: the published route is a phone call, not a form submitted blind. What GOV.UK does not say anywhere is whether HMRC or DWP will read a missing number back to you, or simply deal with the estate using the name, date of birth, date of death, address and death certificate instead. For a living person HMRC is clear that it will not give a National Insurance number out over the phone or by webchat; for someone who has died, the position is not published either way. Have the death certificate and your own identification ready, ask them directly, and take the answer from them rather than from anything written online.
The places you will be asked for it
A handful of processes ask for the number, and none of them come to a halt without it. Tell Us Once asks for it, and GOV.UK notes that giving it helps some organisations match their records faster, with certain public-sector pension schemes needing it outright. Northern Ireland's Bereavement Service asks for it, and the HMRC and DWP lines will ask for whatever identifying details you have; form P1000 has a box for it. The older death-notification form (BD8) is largely superseded: if you use Tell Us Once, you do not normally need to complete it.
The fraud question, answered plainly
Using the identity of someone who has died is a recognised kind of fraud, and it's worth knowing about rather than worrying about. Criminals use a name, date of birth and address to open accounts or apply for credit. Cifas records this in the National Fraud Database, which already takes in death registrations from the General Register Office — so a registered death is flagged without you doing anything. Cifas also offers a paid Protective Registration (£30 for two years) that adds extra checks on the name; it's an option, not a step you need to take. If you think an identity has been misused, report it to Action Fraud at reportfraud.police.uk or 0300 123 2040, or to Police Scotland on 101. One thing that catches families out: data protection law covers living individuals only, so UK GDPR does not govern what HMRC or DWP will disclose about someone who has died.
A short checklist for this step.
Free to use — nothing to sign up for. Work down it at your own pace.
- Nothing to cancel — no one expects you to close a National Insurance number
- Use Tell Us Once when you register: one report reaches both HMRC and DWP
- Without Tell Us Once, call HMRC on 0300 322 9620 and the DWP Bereavement Service on 0800 151 2012
- Look on a payslip, a P60, a P45, or any letter about tax, pensions or benefits
- Check self-assessment or tax-return paperwork if they filed a return
- If it cannot be found, call the HMRC Bereavement Helpline rather than sending form P1000 blind
- Have the death certificate and your own identification ready before you call
- Keep the number with the estate papers — Tell Us Once, DWP, HMRC and P1000 all ask for it
- In Northern Ireland, contact each department separately — Tell Us Once does not operate there
Answered, plainly.
When you are ready — not before. If one missing number has turned into a search for account numbers, policy references and pensions nobody remembered, Executor's First Hour (£179) is prepared by hand for the specific estate you are dealing with, listing what to find and who to tell, in order, and it reaches you within 12 hours. There is nothing to buy to use this page.
Executor's First HourInformational, not legal or financial advice. This guide covers England and Wales; Scotland and Northern Ireland differ. Always confirm current rules and figures at GOV.UK before acting.