What a UTR is (and isn't)
Your UTR (Unique Taxpayer Reference) is the 10-digit number HMRC assigns you when you first register for Self Assessment. It stays with you for life. Without it, you cannot file, and losing it is more common than freelancers expect. This guide covers what a UTR is, where to find yours, and what to do if you've lost it.
What a UTR is (and isn't)
A 10-digit number assigned to every UK taxpayer registered for Self Assessment. Example format: 1234567890. Sometimes written with a suffix K (e.g. 1234567890K) but you enter only the 10 digits when asked.
A UTR is NOT your National Insurance number (that's letters + numbers), not your VAT registration number, not your Companies House company number. They're all distinct identifiers with different purposes.
Where to find yours
Original UTR letter posted by HMRC after registration.
Any Self Assessment paperwork — filing confirmations, statements, penalty notices — all include it.
Your HMRC online account — sign in with Government Gateway → Self Assessment section → UTR displayed.
Historic Self Assessment returns you've filed — the UTR appears on every page.
What to do if you've lost it
Fastest route: sign in to your Government Gateway account and view your Self Assessment section — UTR shown there.
If you can't sign in: call HMRC's Self Assessment helpline (0300 200 3310) with your NI number and personal details. They can post the UTR to your registered address — takes 10-14 days.
Do NOT re-register for Self Assessment thinking you'll get a new UTR — you'll create duplicate records and confusion.
Worked example
Aisha registered for Self Assessment on 3 August 2025. HMRC posted her UTR letter dated 11 August, arriving 15 August. The letter includes: her UTR (1234567890), a Government Gateway activation code (12-digit code, expires 28 days after issue), and notes on what to do next. She activates her Government Gateway account within 28 days. Six months later, when it's time to file, she signs in and her UTR is pre-populated. Her records stay tied to that UTR forever.
Reference table
| Number | What it is | Where to find |
|---|---|---|
| UTR (10 digits) | Self Assessment reference | HMRC letter, online account, SA paperwork |
| NI number (2 letters + 6 digits + letter) | Employment record | P60, payslip, NI card, letters from DWP |
| VAT number (9 digits + suffix) | VAT registration | VAT registration certificate, VAT invoices |
| Company number (8 digits) | Companies House | Certificate of incorporation, gov.uk company search |
| Employer PAYE reference | PAYE registration | P60, HMRC letters about PAYE |
UTR safekeeping checklist
- Save the UTR letter in your Self Assessment paperwork folder
- Take a photo of the letter for backup (encrypted storage recommended)
- Note the UTR in your accounting software's business-details section
- Add UTR to your accountant's record if they file for you
- Include UTR on any invoices sent to HMRC or government bodies (rare but sometimes requested)
- Never share UTR by unsolicited email or phone call — HMRC don't ask for it that way
Usually 10-14 working days by post. Digital-only issuance is being rolled out but paper remains the default.
No — a UTR isn't required. Business bank accounts need proof of ID, address, and business activity, not a UTR.
No. The UTR is required to submit the return. If you've registered but not yet received your UTR by the filing deadline, contact HMRC — they can issue it faster in urgent cases.
No. Your personal UTR stays with you. The limited company gets its own Corporation Tax UTR (also 10 digits, from HMRC when the company registers).
Semi-sensitive. It's not as protected as an NI number or a bank card, but you shouldn't share it publicly. Scammers occasionally combine UTRs with other stolen data to file fake returns.
Sources & official references
Related on FreelanceToolkit UK
This guide is general information based on UK rules for the 2025/26 tax year. It is not personal tax or legal advice. For decisions affecting your tax position or legal exposure, consult a qualified accountant or solicitor.