Your Unique Taxpayer Reference (UTR) is a 10-digit number HMRC assigns when you register for Self Assessment or form a company. You need it to file returns, claim CIS refunds, and deal with HMRC about your tax. Here is every place it hides.
Where to find a UTR you already have
- Any Self Assessment letter from HMRC — the 'Welcome to Self Assessment' letter (SA250), statements, payment reminders.
- Your personal tax account on GOV.UK — under Self Assessment.
- The HMRC mobile app — same place.
- Previous tax returns, or your accountant's records.
- For a limited company: the company's own UTR arrives by post shortly after incorporation and appears on Corporation Tax letters.
Lost it completely?
Call HMRC's Self Assessment line or request it through your personal tax account — they post it to the address on record, which takes up to two weeks. They will not give a UTR over the phone or by email, so start before any deadline gets close.
Never had one?
Then you're not registered for Self Assessment yet. If you've started working for yourself, registration (the CWF1 route) should happen by 5 October after the end of your first tax year. We register clients same-day and the UTR follows by post — done properly the first time, with your first return set up from the start.