A UTR number is the Unique Taxpayer Reference that HM Revenue and Customs assigns you for Self Assessment. It is 10 or 13 digits long, stays with you for life, and identifies you on every return, payment, and letter that passes between you and HMRC. If HMRC has already issued you one, you can find it on their correspondence, in your Personal Tax Account, or in the HMRC app. If you have never had one, you get it by registering for Self Assessment.
Where to Find a UTR You Already Have
HMRC prints your UTR on most of the letters it sends you about Self Assessment. It usually sits near the top of the page, labelled “UTR,” “Tax reference,” or simply “Reference.”1GOV.UK. Find Your UTR Number Good places to check:
- The annual notice to file a tax return.
- Any previous Self Assessment return you have kept.
- Payment reminders and statements of account.
If you run a limited company, your Corporation Tax UTR appears on the letters HMRC has sent about that account.2GOV.UK. Add Corporation Tax Services to Your Business Tax Account
In Your Personal Tax Account
The Personal Tax Account is a GOV.UK dashboard where you can check your Income Tax estimate, manage Self Assessment, and see your UTR.3GOV.UK. Personal Tax Account: Sign In or Set Up Sign in with your Government Gateway user ID and password, then open the Self Assessment section. The UTR is shown there alongside your balance and filing deadlines.
In the HMRC App
The free HMRC app, on iOS and Android, uses the same Government Gateway credentials. Once you sign in, your UTR appears in the Self Assessment area.1GOV.UK. Find Your UTR Number
How to Get a UTR If You Do Not Have One
You receive a UTR when you register for Self Assessment or when you set up a limited company.1GOV.UK. Find Your UTR Number The route depends on why you need to file.
If You Are Self-Employed
Sole traders register for Self Assessment and Class 2 National Insurance together, using form CWF1 on GOV.UK. You will need a Government Gateway user ID (you can create one during registration), your National Insurance number, your full name, date of birth, address, and the date your self-employment started.4GOV.UK. Check How to Register for Self Assessment
If You Are Not Self-Employed
If you need to file for another reason, such as rental income, taxable foreign income, the High Income Child Benefit Charge, or Capital Gains Tax, register using form SA1 instead. You will need your name, address, date of birth, a daytime phone number, your National Insurance number if you have one, the reason you are registering, and the date the liability started.5GOV.UK. Register for Self Assessment if You Are Not Self-Employed
If You Do Not Yet Have a National Insurance Number
You can still register. Use form SA1 rather than CWF1, and complete the section that asks why you cannot provide a National Insurance number. This route is open even if you are self-employed, but you should apply for a National Insurance number separately as soon as you can.5GOV.UK. Register for Self Assessment if You Are Not Self-Employed
The Registration Deadline
You must tell HMRC by 5 October following the end of the tax year in which you first became liable.4GOV.UK. Check How to Register for Self Assessment If you started earning self-employed income during the 2025/26 tax year (6 April 2025 to 5 April 2026), you would need to register by 5 October 2026. Missing the deadline can trigger a “failure to notify” penalty based on the tax owed and whether HMRC treats the behaviour as deliberate. Registering on time also gives you the UTR well before the 31 January filing date.
How Long It Takes
HMRC does not issue the UTR instantly. It posts the number to the address you gave, usually within about 15 working days, and longer if you live outside the UK.1GOV.UK. Find Your UTR Number A separate activation code arrives by post to finish setting up your online Self Assessment account. If it does not arrive or has expired, you can request a new one through your Government Gateway account.2GOV.UK. Add Corporation Tax Services to Your Business Tax Account Keep both letters safe.
Recovering a Lost UTR
If you cannot find your UTR on any document or in your online account, contact HMRC.1GOV.UK. Find Your UTR Number The Self Assessment helpline is 0300 200 3600, or +44 161 930 8445 from outside the UK, open Monday to Friday, 8am to 6pm, closed on bank holidays.6GOV.UK. Self Assessment: Online Technical Support A digital assistant is available on GOV.UK too.
For security, HMRC will not read the UTR out over the phone. It sends a letter with the number to the address on file. If your address has changed, update it first through your Personal Tax Account or by calling the helpline.
UTRs for Partnerships, Trusts, and Limited Companies
Individuals are not the only ones with UTRs. Each of these has its own registration process and its own reference.
Partnerships
The nominated partner registers the partnership on form SA400, online or by post, and HMRC issues a UTR for the partnership. Every individual partner also needs a personal UTR, which means registering separately for Self Assessment if they do not already have one. HMRC usually responds within 15 working days.7GOV.UK. Register a Partnership for Self Assessment
Trusts
Trustees register through HMRC’s Trust Registration Service. You need an Organisation Government Gateway user ID, and a separate Organisation account for each trust you manage. HMRC posts the UTR to the lead trustee, typically within 15 working days. If the trust is not liable to pay tax, the reference can instead be found by signing back into the Trust Registration Service after submitting the registration.8GOV.UK. Register a Trust as a Trustee
Limited Companies
When you incorporate at Companies House, HMRC is notified automatically and posts a Corporation Tax UTR to your registered office. If it has not arrived within 15 working days of company registration, you can request it through your business tax account.2GOV.UK. Add Corporation Tax Services to Your Business Tax Account
Keeping Your UTR Safe
Treat the UTR as a sensitive identifier. HMRC will never email, text, or phone you to ask for your UTR, passwords, or banking details, and it will not leave voicemails threatening arrest or legal action.9GOV.UK. Scams Warning as Self Assessment Customers Targeted Share the number only when you are certain you are dealing with HMRC directly or with a trusted professional such as your accountant.