Daily Junction.mobi portalBusiness · August 26, 2023 · Marcus Vale · 6 min
A UTR is your Unique Taxpayer Reference, a 10-digit number HMRC uses to identify you for Self Assessment and tax. This guide explains what it is, where to find it, and how it differs from other tax numbers.
If you have ever registered as self-employed or set up a company, you will sooner or later be asked for your UTR. It stands for Unique Taxpayer Reference, and it is the 10-digit number HMRC uses to tell one taxpayer from another. You need it to file a tax return, and you will be prompted for it repeatedly when dealing with HMRC — yet it is easy to confuse with the other reference numbers floating around, like your National Insurance number or your company registration number. This guide explains what a UTR is, how to get one, where to find it, and how it differs from those other numbers. This is general information, not tax advice.
A UTR, or Unique Taxpayer Reference, is a 10-digit number that HMRC uses to identify you for tax purposes. Think of it as your personal account number with the tax system. Every taxpayer who needs one has their own, and it stays with you — it does not change from year to year.
A UTR is most closely associated with Self Assessment, the system through which people who do not have all their tax collected automatically through payroll report their income and pay what they owe. If you complete a tax return, your UTR is how HMRC links that return to you.
Both individuals and companies have UTRs:
The number is always 10 digits, sometimes shown with a letter K on the end in certain contexts. It is a reference, not a password — but because it identifies you to HMRC, it should still be kept secure.
You need a UTR if you have to deal with HMRC through Self Assessment or Corporation Tax. Common situations include:
If your tax is dealt with entirely through PAYE and you never need to file a return, you may never be issued a personal UTR — many employees do not have one. It is the act of needing to report tax yourself that brings a UTR into your life.
The reassuring thing is that you do not apply for a UTR separately. It is issued automatically as part of registering for tax. The trigger depends on your situation:
After you register, HMRC sends the UTR to you, normally by post within about ten working days (longer if you are abroad). Because of that delay, it pays to register in good time rather than close to a filing deadline — waiting for a UTR to arrive is a common cause of last-minute panic. Registering for Self Assessment is itself part of the wider process explained in our Self Assessment tax return guide.
A UTR arrives by post a week or two after you register — so leave a buffer. Many people only realise they need their UTR when the return is due, by which point the clock is against them.
Once you have a UTR, it crops up in several places, so a lost one is rarely lost for good. Look for it on:
It is sometimes labelled simply tax reference or Unique Taxpayer Reference rather than UTR. If you genuinely cannot find it anywhere, you can contact HMRC, who can confirm it — they will need to verify your identity first, and they will typically post it to your registered address rather than read it out, for security.
This is where most confusion arises, because the UK tax and company systems use several different reference numbers. They are not interchangeable.
| Number | What it is for | Format | Issued by |
|---|---|---|---|
| UTR | Self Assessment / tax returns | 10 digits | HMRC |
| National Insurance number | Tracking National Insurance | 2 letters, 6 digits, 1 letter | HMRC/DWP |
| Company registration number | Identifying a company | 8 characters | Companies House |
| VAT number | VAT-registered businesses | 9 digits (with GB prefix) | HMRC |
A few clarifications worth holding on to:
Keeping these straight saves real time, because using the wrong number on a form or payment can cause delays or misallocated payments.
A UTR is sensitive information. While it is not a password, it can be used in attempts at tax fraud or identity theft, so treat it with care:
If you use an accountant, they will need your UTR to file on your behalf, which is a legitimate use. The key is sharing it deliberately, with people you have chosen, rather than in response to a message that arrives out of the blue.
A UTR — Unique Taxpayer Reference — is the 10-digit number HMRC uses to identify you or your company for tax, above all for Self Assessment and Corporation Tax. You get one automatically when you register for Self Assessment or set up a limited company, and it arrives by post within a couple of weeks, so register in good time. You will need it to file returns, and you can find it on HMRC letters and in your online account. Crucially, it is not the same as your National Insurance number, your company registration number or your VAT number. Keep it secure, watch out for scams, and treat HMRC and GOV.UK as the authoritative sources.
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