Where to Find Your UK Tax Identification Number

The UK does not issue a single document called a tax identification number. For almost every individual, the number that functions as a UK tax identification number is the National Insurance (NI) number. If you file a Self Assessment return or run a limited company, you also have a Unique Taxpayer Reference (UTR), and HMRC treats both the NI number and the UTR as TIN equivalents when foreign banks or tax authorities ask.¹

Which Number Counts as Your UK TIN

This is usually what sends people searching: a foreign bank, broker, or employer asks for a “Tax Identification Number” and nothing on your UK paperwork carries that exact label. The UK simply doesn’t print one. The OECD recognises two UK numbers as TIN equivalents, and HMRC’s own Common Reporting Standard guidance confirms the position.

If you’re an individual UK resident, give your National Insurance number. It has the format of two letters, six digits, and a final letter, for example QQ 12 34 56 B.²
If you’re self-employed, or the account relates to business income, you may be asked for your Unique Taxpayer Reference instead. The individual UTR is 10 digits; a company UTR is also issued by HMRC on Corporation Tax correspondence.³

When in doubt, start with the NI number. Hand over a UTR only if the form specifically asks for a tax reference tied to Self Assessment or a company.

Where to Find Your National Insurance Number

Your NI number shows up on most tax paperwork you already have. Check:

Your payslips.
Your P60, the annual summary your employer gives you after each tax year ends.
Any letter from HMRC or the Department for Work and Pensions about tax, benefits, or pensions.²

If none of those are to hand, sign into your Personal Tax Account on GOV.UK or open the HMRC app. Both display the number once you’ve confirmed your identity, usually with a passport or driving licence.⁴

Where to Find Your Unique Taxpayer Reference

For an individual UTR, look at previous Self Assessment tax returns, notices to file a return, or payment reminders from HMRC. The number is sometimes labelled “reference,” “UTR,” or “official use” rather than written out in full.⁵ It also appears in your Personal Tax Account and the HMRC app.⁶

A limited company’s UTR appears on Corporation Tax letters from HMRC, including the CT603 notice to deliver a company tax return. If you have never received one, you can request the Corporation Tax UTR online and HMRC will post it to the address held at Companies House.⁶

Partnership UTRs sit in the Business Tax Account, the HMRC app, and on partnership tax returns.⁵

VAT and PAYE Numbers for Businesses

If you run a VAT-registered business, your VAT Registration Number is printed on the VAT registration certificate HMRC issued when you first registered, and it’s also visible in your VAT online account.⁷ To verify someone else’s UK VAT number, use the free “Check a UK VAT number” service on GOV.UK.

Employers have a separate PAYE Reference, formatted as a three-digit tax office number, a forward slash, and up to ten letters or numbers (for example, 123/AB456). It appears on HMRC letters about PAYE, on employees’ P45 and P60 forms, and inside your payroll software.⁸

If You’ve Never Had a UK Tax Number

Applying for a National Insurance Number

If you’ve moved to the UK and never had an NI number, apply online through GOV.UK. You’ll need a passport from any country, or a national identity card from an EU country, Norway, Liechtenstein, or Switzerland. During the application you may be asked to upload a photo of yourself holding your passport, along with photos of other identity documents.⁹

Without those documents you can still apply, but you may need an in-person appointment to prove your identity. After identity is confirmed, the number arrives within about four weeks.⁹

Registering for Self Assessment to Get a UTR

A UTR is issued when you register for Self Assessment. The deadline is 5 October following the end of the tax year in which you first need to file. For income earned in the 2024–25 tax year, that meant registering by 5 October 2025. Registering late can trigger a “failure to notify” penalty based on any unpaid tax.¹⁰

After you register online, HMRC posts the UTR within about 15 days. It takes longer if you live outside the UK.⁶ You can check current reply times on GOV.UK if you’re still waiting.¹¹

If You’ve Lost Your Number

Lost National Insurance Number

The fastest route is the online “Find your National Insurance number” service on GOV.UK, which shows it immediately once you prove your identity with a passport or driving licence.¹² If that doesn’t work, you can ask HMRC to post a confirmation letter (up to 10 working days for UK residents, 21 if you’re abroad), or complete form CA5403 online, print and sign it, enclose identity documents, and post it to HMRC.¹³

Lost UTR

Check your Personal Tax Account or the HMRC app first; both show the UTR instantly once you’ve signed in. If that’s not possible, call the Self Assessment helpline on 0300 200 3600. HMRC will verify your identity and post the UTR, which usually takes around 15 days.⁶

Lost VAT Number or PAYE Reference

For a lost VAT Registration Number, sign into your VAT online account where the number is displayed. HMRC’s digital assistant also handles VAT general enquiries. The VAT phone helpline exists, but HMRC’s security checks often require the very number you’re trying to recover, so the online route is usually quicker.⁷ For a lost PAYE Reference, look at any HMRC letter about your PAYE scheme, employees’ P45 or P60 forms, or your payroll software settings before calling HMRC’s employer helpline.

Keeping These Numbers Safe

Your NI number and UTR are keys to your tax identity. Anyone who holds them can attempt to file fraudulent returns or get into your HMRC account. HMRC’s guidance is to share your NI number only with people and organisations that genuinely need it.¹⁴

If something looks wrong in your HMRC online account, change your password straight away and report the suspicious activity through the security console in HMRC online services. You’ll need your NI number, an email address, a contact phone number, and details of what looks off. Acting quickly helps HMRC lock down your records before any further damage is done.¹⁴

1
GOV.UK. HMRC Internal Manual – IEIM402040 – Reportable Information: Tax Identification Number CRS
2
GOV.UK. National Insurance: Introduction – Your National Insurance Number
3
GOV.UK. HMRC Internal Manual – IEIM902330 – Tax Identification Number (TIN)
4
GOV.UK. Personal Tax Account: Sign In or Set Up
5
HM Revenue & Customs. Unique Taxpayer Reference – HMRC Patterns for Services
6
GOV.UK. Find Your UTR Number
7
GOV.UK. VAT: General Enquiries
8
HM Revenue & Customs. Employer PAYE Reference – HMRC Patterns for Services
9
GOV.UK. Apply for a National Insurance Number – How to Apply
10
GOV.UK. Self Assessment Tax Returns: Penalties
11
GOV.UK. Check How to Register for Self Assessment
12
GOV.UK. Find Your National Insurance Number
13
GOV.UK. Get Your National Insurance Number by Post
14
GOV.UK. Report Suspicious Activity Happening in Your HMRC Online Account