Scope: This guide focuses on an individual’s or sole trader’s Self Assessment Unique Taxpayer Reference. Company, partnership and trust references belong to the relevant organisation.
The short answer
A Unique Taxpayer Reference, commonly shortened to UTR, is a 10-digit reference. HMRC issues one when a person registers for Self Assessment; a limited company also receives its own UTR when set up.
An individual can find the Self Assessment UTR in the Personal Tax Account, HMRC app, previous returns, notices to file and payment reminders.
If you have never registered and need to file, use the Self Assessment registration route. Searching for a lost UTR does not create one. HMRC says a newly issued reference usually arrives by post around 15 days after registration, with longer waits overseas.
What the UTR identifies
The UTR links records and submissions to the correct taxpayer within HMRC’s systems. It may appear on documents simply as “tax reference”. Treat it as sensitive tax information even though it is not a password.
Do not confuse it with:
- a National Insurance number;
- a PAYE employer reference;
- a Corporation Tax UTR belonging to a company;
- a VAT registration number; or
- an 11-character Self Assessment payment reference, which commonly adds
Kto the 10-digit UTR.
Using the wrong entity’s reference can misroute a return, authorisation or payment.
Where an individual can look
Start with official digital records:
- Sign in to the Personal Tax Account.
- Check the Self Assessment area.
- Check the HMRC app if already set up.
- Look at a previous tax return or calculation.
- Look at notices to file, statements and payment reminders.
Search securely. Do not email a full UTR unnecessarily or upload it to an unofficial “finder” service.
If you cannot find it
Use HMRC’s find-your-UTR guidance. If the number is absent from the account, app and documents, contact HMRC using the official link on that page. HMRC will need to establish identity before disclosing tax information.
Allow enough time before a filing deadline. The reference may not be delivered instantly, particularly where registration, address or identity records need resolving.
If you have not registered
First check whether you need to send a return, then register for Self Assessment. The process depends on whether you are self-employed, not self-employed, a partner or acting for another type of taxpayer.
A new registration and a search for an existing reference are different actions. Registering again without checking can create delay or duplicate records. If you previously filed, follow HMRC’s reactivation instructions rather than automatically opening another record.
Company and organisation references
A company has a Corporation Tax UTR separate from its director’s personal UTR. HMRC sends company information to the registered office and provides a specific online request route where the company UTR is missing.
Partnerships and trusts can also have their own references. When acting for an organisation, use documents issued to that organisation and the correct authorisation. Do not substitute a partner’s or trustee’s personal number.
Using the UTR safely
- Enter it only into the official return, payment or authorisation flow that asks for it.
- Check all ten digits against an HMRC source document.
- Store it in controlled tax records.
- Redact it from screenshots used for general support.
- Never treat possession of a UTR as proof that a caller is HMRC.
- Start from GOV.UK when contacting HMRC.
Common mistakes
- Calling every tax reference a UTR.
- Using the company UTR on a director’s personal return.
- Adding the payment suffix when a form asks for the 10-digit UTR only.
- Registering again because an old reference cannot immediately be found.
- Waiting until filing day to recover sign-in details and the UTR.
- Sharing the number with an unverified refund agent.
What to do next
- Check the Personal Tax Account and HMRC app.
- Review old returns and official HMRC letters.
- Use HMRC’s find-your-UTR route if still missing.
- Register only if no Self Assessment record exists and registration is required.
- Verify the reference before filing or paying.