What a UTR looks like
A personal UTR is 10 digits, often written in two groups of five, like 12345 67890. Some documents show it with a letter K on the end (for example 1234567890K) — that's the payment reference format, not part of the UTR itself.
It is different from your National Insurance number (two letters, six numbers, one letter) and from a company UTR, which belongs to a limited company rather than to you personally. See what a UTR is for the difference.
5 places to find your UTR
1. The HMRC app
Sign in to the free HMRC app and open the Self Assessment section. Your UTR is shown there, and you can copy it straight into a form. This is usually the fastest option if you've used the app before.
2. Your Personal Tax Account
Sign in to your Personal Tax Account on GOV.UK with your Government Gateway or GOV.UK One Login details. Go to the Self Assessment section — your UTR is displayed at the top.
3. A previous tax return
If you've filed before, your UTR is on the first page of a paper SA100 and on the summary of an online return. Check any copies you or your accountant kept.
4. HMRC letters and statements
Look for a Notice to file, a Self Assessment statement, a payment reminder or the welcome letter HMRC sent after you registered. The UTR is usually near the top, labelled “Tax reference” or “UTR”.
5. Your accountant or agent
If an accountant has filed for you before, they will have your UTR on file and can tell you.
Useful tool
Got a number but not sure it's your UTR? Check the format in seconds.
Still can't find it?
You can ask HMRC to post your UTR to you. Use the “lost UTR” option on GOV.UK or call the Self Assessment helpline. For security reasons HMRC won't tell you the number over the phone — they send it by post to the address they hold, which usually takes up to about two weeks.
Deadline close?
If the 31 January deadline is near and you're waiting for a posted UTR, start your return preparation now so you're ready to submit the moment it arrives. Penalties start at £100 the day after the deadline — see Self Assessment penalties.If you've never had a UTR
You only get a personal UTR after registering for Self Assessment. If you're newly self-employed, renting out property, or have other untaxed income, you'll need to register for Self Assessment — HMRC then posts your UTR, usually around 15 days later.
Not sure you need to register at all? Use our guide on whether you need to file a tax return.
Using your UTR with TaxGo
When you start your return on TaxGo, you'll be asked for your UTR once. If you upload an HMRC letter that shows it, TaxGo reads it from the document so you don't have to type it.