Your UTR Number Explained

How to Get Your UTR Number

A UTR (Unique Taxpayer Reference) is a 10-digit number that HMRC assigns to you when you register for Self Assessment. It’s your personal identifier for all Self Assessment correspondence and transactions.^[1]

It’s sometimes written with spaces (e.g. 12345 67890) but is always 10 digits. Don’t confuse it with your National Insurance number — they’re different things used for different purposes.

Where to Find Your UTR

There are several places you can find your UTR:^[1]

SA250 letter — the welcome letter HMRC sent when you first registered for Self Assessment
Previous tax returns — your UTR appears on all Self Assessment correspondence
HMRC online account — log in to your personal tax account to view it
HMRC app — available in the app once you’re logged in
Notice to file (SA316) — the annual reminder HMRC sends before each filing deadline
Payment reminders — any statements or payment reminders from HMRC

How to Get a UTR

You get a UTR automatically when you register for Self Assessment. HMRC sends it by post, usually within 10 working days (21 days if you’re abroad).^[3]

If you haven’t registered yet, you’ll need to do that first — see our registration guide.

Lost Your UTR?

If you can’t find your UTR:^[1]

Check your HMRC online account — log in via Government Gateway and it’s displayed on your Self Assessment dashboard
Check the HMRC app
Call HMRC — Self Assessment helpline on 0300 200 3310. You’ll need to verify your identity with your name, address, date of birth, and National Insurance number

Tip: Save your UTR somewhere secure and accessible (a password manager, for example). You’ll need it for filing, payments, and any contact with HMRC — including when you file your Income Tax return online.

UTR vs National Insurance Number

UTR	National Insurance Number
10 digits (numbers only)	2 letters, 6 numbers, 1 letter (e.g. AB 12 34 56 C)
Used for Self Assessment only	Used for tax, NI, benefits, and State Pension
Issued when you register for SA	Issued automatically before your 16th birthday
You may not have one	Everyone with the right to work in the UK has one

Keeping Your UTR Safe

Your UTR should be treated like sensitive financial information. While it can’t be used to access your account on its own, someone who knows your UTR could potentially impersonate you in written correspondence with HMRC.^[5]

Don’t share it publicly, and be cautious of unsolicited emails or calls asking for your UTR — HMRC will never ask for your full UTR by email.

Frequently Asked Questions

What is a UTR number?

A UTR (Unique Taxpayer Reference) is a 10-digit number assigned by HMRC when you register for Self Assessment. It is your personal identifier for all Self Assessment correspondence, filing, and payments.

Where can I find my UTR number?

You can find it on your SA250 welcome letter, previous tax returns, HMRC online account, the HMRC app, or any Self Assessment correspondence such as the annual notice to file or payment reminders.

How do I get a UTR number?

You receive a UTR automatically when you register for Self Assessment. HMRC sends it by post within about 10 working days (21 days if abroad). You must register first at gov.uk/register-for-self-assessment.

What is the difference between a UTR and a National Insurance number?

A UTR is a 10-digit number used only for Self Assessment. A National Insurance number has letters and numbers (e.g. AB 12 34 56 C) and is used for tax, NI contributions, benefits, and the State Pension.

Sources

Find your UTR number — GOV.UK
Self Assessment tax returns — GOV.UK
Register for Self Assessment — GOV.UK
HMRC online services: sign in or set up an account — GOV.UK
Get help with Self Assessment — GOV.UK

Your UTR Number: What It Is and How to Find It