Key takeaways
- A Unique Taxpayer Reference (UTR) is a 10-digit number HMRC gives you when you register for Self Assessment or set up a limited company.
- The quickest places to find your UTR are the HMRC app and your personal tax account.
- On paper, your UTR is on past tax returns and HMRC letters such as notices to file and payment reminders, often labelled Reference, UTR or Official use.
- HMRC usually posts a new UTR about 15 days after you register for Self Assessment; it takes longer if you live abroad.
- If you cannot find your UTR anywhere, call the Self Assessment helpline on 0300 200 3310, Monday to Friday, 8am to 6pm.
- A limited company can ask for a copy of its Corporation Tax UTR online, and HMRC posts it to the registered office address held by Companies House.
- You need your UTR to file a Self Assessment return by the 31 January 2027 online deadline for the 2025/26 tax year.
Your UTR (Unique Taxpayer Reference) is a 10-digit number HMRC gives you when you register for Self Assessment or set up a limited company. The fastest places to find it are the HMRC app and your personal tax account. It is also printed on past tax returns and most HMRC letters about Self Assessment.
What is a UTR number?
A UTR is your tax reference for Self Assessment, or a company’s reference for Corporation Tax. GOV.UK says it is 10 digits long and may simply be called a “tax reference”. HMRC’s own design guidance tells HMRC services to accept 10 or 13 digits, with or without a letter K at the start or end, so you may see it written those ways too.
You need your UTR to file a tax return, to pay a Self Assessment bill and to pass security when you call HMRC. With the Self Assessment deadline for 2025/26 returns on 31 January 2027, now is the time to find it.
The five places to look
Check these in order. The first two work in minutes if you can sign in.
| Where | Who it works for | Speed |
|---|---|---|
| 1. HMRC app | Individuals, sole traders | Instant |
| 2. Personal tax account | Individuals, sole traders | Instant |
| 3. Your registration letter | Anyone newly registered | Arrives by post |
| 4. Past tax returns | Anyone who has filed | Instant if kept |
| 5. Other HMRC letters | Individuals, companies, partnerships | Instant if kept |
1. The HMRC app
The HMRC app shows your UTR in your Self Assessment details. Download it on iPhone or Android and sign in with your Government Gateway or GOV.UK One Login details.
2. Your personal tax account
Your personal tax account on GOV.UK also shows your UTR in the Self Assessment section. If you have trouble signing in, see our guide to the HMRC online account or the online services helpdesk.
3. The letter HMRC sent when you registered
HMRC posts your UTR after you register for Self Assessment. It usually arrives about 15 days after you register, and later if you live abroad.
4. Past tax returns
Any Self Assessment return you have filed, or a copy saved from software, shows your UTR. Accountants also keep it on file, so ask yours if you use one.
5. Other HMRC letters
Notices to file a return, statements and payment reminders all carry the UTR. HMRC says it can be labelled Reference, UTR or Official use. Company UTRs appear on Corporation Tax letters and returns.
Which applies to you?
The right route depends on who the UTR belongs to.
- You are self-employed or a landlord: use the app or personal tax account first.
- You have just registered: wait about 15 days for the letter before chasing.
- You run a limited company: check Corporation Tax letters, then request a copy online (see below).
- You are in a partnership: the partnership UTR is in the business tax account, the HMRC app and partnership returns.
- You have never registered: you do not have a UTR yet. Check who needs to file and register first.
How do I get my UTR from HMRC if it is lost?
Call the Self Assessment helpline if you cannot find your UTR in any document or online. The contact details are:
- UK: 0300 200 3310
- outside the UK: +44 161 931 9070
- hours: Monday to Friday, 8am to 6pm, closed on bank holidays
HMRC’s digital assistant can also help, with a transfer to webchat if an adviser is free. Our guide to the best time to call HMRC can save you a long wait.
How does a limited company find its UTR?
A company can ask for a copy of its Corporation Tax UTR through HMRC’s online request service. You need:
- the company registration number
- the registered company name
HMRC then posts the UTR to the registered office address held by Companies House, to keep it secure. The service does not work for companies that have been dissolved or struck off, and newly incorporated companies cannot use it; HMRC says their UTR should arrive at the registered address soon after incorporation.
A company UTR is different from the company number Companies House gives you. Our guide to UK tax identification numbers explains every reference you might be asked for.
What to do now
- Find your UTR today and save it somewhere safe.
- Check you can sign in to your personal tax account.
- If you have never registered but need to file for 2025/26, register now, since the UTR takes about 15 days to arrive.
- Estimate your bill with our Self Assessment calculator.
Frequently asked questions
How many digits is a UTR number?
GOV.UK says a UTR is 10 digits. Some HMRC systems show it as 13 digits or with a K at the start or end.
Where is my UTR on an HMRC letter?
Look for a heading such as Reference, UTR or Official use. It is usually near the top of notices to file, statements and payment reminders.
How long does it take to get a UTR?
HMRC usually posts it about 15 days after you register for Self Assessment. It takes longer if you live abroad.
Can I get my UTR over the phone?
Yes. Call the Self Assessment helpline on 0300 200 3310, Monday to Friday, 8am to 6pm, if you cannot find it elsewhere.
Is my UTR the same as my National Insurance number?
No. Your National Insurance number is a personal reference with two letters, six numbers and a letter. Your UTR is a separate 10-digit tax reference.
Sources
Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance on 6 November 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.