A UTR number is your Unique Taxpayer Reference: a 10-digit number HMRC issues when you register for Self Assessment or set up a limited company. It identifies your tax records for Self Assessment or Corporation Tax, and you need it to file returns, pay most tax bills and register for some HMRC schemes. Individuals can find theirs in their Personal Tax Account, in the HMRC app, or on letters and returns from HMRC. It normally arrives by post around 15 days after you register.
What a UTR is, and what it is not
HMRC gives a UTR to each taxpayer that has to deal with it directly through a return. Documents sometimes just call it a "tax reference". Typical holders include:
- Individuals in Self Assessment. Anyone who registers to file a personal tax return, including sole traders and the individual partners in a partnership;
- Limited companies. A company gets its own UTR for Corporation Tax when it is set up;
- Partnerships and trusts. These organisations have their own UTRs, separate from those of the partners or trustees.
A director who files a personal return therefore has two different UTRs to deal with: their own and the company's. Mixing them up is one of the most common reasons a payment or filing goes astray.
A UTR is not your National Insurance number. That has 2 letters, 6 numbers and a final letter (for example QQ123456B), stays the same for life, and records your contributions and tax under PAYE. An employee taxed only through PAYE who has never registered for Self Assessment will have an NI number but no personal UTR.
How to find your UTR
For an individual or sole trader, HMRC lists three places:
- Your Personal Tax Account on gov.uk;
- The HMRC app;
- Paper or online documents from HMRC. Previous tax returns, notices to file a return and payment reminders.
For a company, partnership or trust, the UTR is on previous returns and HMRC notices. A limited company can also request its Corporation Tax UTR online. HMRC posts it to the business address registered with Companies House, so someone needs to pick up the post there. If none of these work, the remaining route is to contact HMRC.
How to get a UTR if you do not have one
You get a UTR by registering. For individuals, that means registering for Self Assessment. The legal deadline comes from section 7 of the Taxes Management Act 1970: if you have not been sent a return, you must tell HMRC you are chargeable within six months of the end of the tax year. In practice that is 5 October.
For the 2025/26 tax year, which ended on 5 April 2026, the deadline was 5 October 2026. It applied if you had not sent a return before, or had registered before but did not need to send one for 2024/25. If you register after that date, HMRC's guidance says it will write to confirm your filing deadline, which will be 31 January 2027 or 3 months from the date on the letter, whichever is later, and you could get a penalty for late notification. The tax itself is still due by 31 January 2027 either way.
The UTR usually arrives by post about 15 days after registration, and later if you live abroad. HMRC has an online tool to check when you can expect a reply. If you have registered before and just need to send a return again, you may have to reactivate your existing account rather than get a new UTR.
For companies, registering the company at Companies House gives the option to set up Corporation Tax at the same time, which produces the company's UTR.
What you need it for
Once issued, the UTR shows up across your dealings with HMRC:
- Filing a Self Assessment return. The 2025/26 online return is due by 11:59pm on 31 January 2027, and a paper return by 31 October 2026;
- Paying Self Assessment tax. The payment reference is 11 characters: your 10-digit UTR followed by the letter K. Using the wrong reference can delay the payment or send it to a different tax bill;
- Construction Industry Scheme. A subcontractor needs the business's UTR to register for CIS. Contractors must deduct 30% from unregistered subcontractors instead of 20%. See our guide to CIS tax;
- Partnership returns. The partnership has its own UTR, separate from each partner's personal UTR, and the registering partner's details, including their UTR, may be needed when a partnership registers for CIS. See our guide to partnership tax returns.
The UTR also sits behind the Self Assessment calendar that follows registration. If you are an employee or pensioner and want an amount you owe collected through your tax code instead of paid in one sum, HMRC says the online return must be in by 11:59pm on 30 December 2026. If you make payments on account, there is a second payment deadline of 31 July, alongside 31 January. Both are tied to the same UTR, and HMRC's letters about either will quote it.
Corporation Tax payments do not use the UTR on its own. They use a 17-character payment reference that changes with each accounting period, so a company needs the reference for the specific period it is paying rather than an old one.
Keeping it safe
Treat the UTR as you would your National Insurance number. Share it with HMRC and with people who need it to deal with HMRC on your behalf, and not more widely. If you start self-employment for the first time, register promptly rather than waiting for the deadline. Our guide to the new self-employed tax rules covers the obligations that follow.
Acumon handles Self Assessment registration and returns through its self-assessment service, including chasing a missing UTR and reactivating dormant records. New companies set up through our company formation service are registered for Corporation Tax at the same time.