What is a UTR number?

Where to find your UTR

1. On HMRC letters. It appears on your tax return, statements and most correspondence from HMRC.
2. In your Personal Tax Account or the HMRC app, under your Self Assessment details.
3. On a payment reference. Your Self Assessment payment reference is your UTR followed by the letter K.

How to get one, and lost UTRs

You get a UTR by registering for Self Assessment, after which HMRC posts it within about 10 working days. If you have lost yours, you can find it in your online account or the app, or ask HMRC. A company also has its own separate UTR for corporation tax.

What it is, and what it is not

A Unique Taxpayer Reference is a 10 digit number HMRC uses to identify you for Self Assessment or your company for Corporation Tax. You get one when you register for Self Assessment, and a company gets one automatically when it is incorporated.

It is worth being clear about what it is not, because these get confused constantly.

• It is not your National Insurance number, which is two letters, six digits and a letter and stays with you for life.
• It is not your company registration number, which comes from Companies House.
• It is not a VAT number, which begins GB and has nine digits.
• You can have two UTRs quite legitimately, one personal and one for your company. They are different numbers and using the wrong one sends a payment to the wrong place.

Getting one, and how long it takes

You register for Self Assessment online. HMRC then posts the UTR to you, and it usually arrives in about 15 days, longer if you live abroad.

That waiting period is the reason to register early. If you leave it until January, the number may not arrive before the filing deadline, and you cannot file without it. The penalty for filing late applies whether or not the delay was caused by waiting for a number you asked for too late.

The registration deadline

You must tell HMRC you need to complete a tax return by 5 October following the end of the tax year in which the liability arose. Start self employment in June 2026, which sits in the 2026/27 tax year, and the deadline is 5 October 2027.

Missing it is a failure to notify penalty, and it is a percentage of the tax you owed rather than a flat fee. If it was not deliberate and you come forward yourself within 12 months of the tax being due, the penalty can be reduced to nil. If HMRC approaches you first, it starts at 10% of the tax and rises. Deliberate concealment can reach 100%.

The lesson is simple: telling HMRC voluntarily is almost always cheaper than being found.

Finding a UTR you have lost

Before assuming it is gone, look in these places. It is usually one of them.

• Your Personal Tax Account or the HMRC app, which is the quickest route.
• Any previous tax return, or your notice to file.
• Payment reminders and statements of account from HMRC.
• For a company, the first letter HMRC sent to the registered office after incorporation.

If it is genuinely lost you can ask HMRC to send it again, but it goes by post to the address they hold, so make sure that address is current first.

Where you will actually need it

Filing your tax return. Paying your tax, where the payment reference is your UTR followed by the letter K. Registering for CIS. Applying for gross payment status. Giving details to a contractor or agency who needs to verify you. Authorising an accountant to act for you.

Getting the payment reference wrong is the most common practical problem. A payment made without the correct UTR reference sits unallocated at HMRC while penalties and interest continue to build on an account that looks unpaid.

Keeping it safe

Your UTR is not a secret in the way a password is, but combined with your name, date of birth and address it is enough for someone to attempt to file in your name or claim a refund. Do not post it in public, and be sceptical of anyone who contacts you asking for it alongside your bank details. HMRC will not ring you out of the blue asking for a UTR and a card number.

Frequently asked questions