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What is a UTR number?

Find out what a unique tax reference (UTR) number is, how you can get one from HMRC and what you'll need to use it for.

In this article
What is a UTR number? Who needs a UTR number from HMRC? How do I get a UTR number?
Information needed to register Your UTR questions answered

What is a UTR number?

A UTR number is your ‘unique taxpayer reference’ number. HMRC assigns each self-assessment taxpayer a different number in order to track their tax records.

All UTR numbers have 10 digits, and sometimes there's a letter 'K' at the end. 

Once you get your UTR number it stays with you all your life - in the same way as your National Insurance number.


Who needs a UTR number from HMRC?

You only need a UTR number if you submit a self-assessment tax return - meaning if you're self-employed or have set up a limited company, you will need a UTR number to pay tax. 

If you're not sure whether you need one, see our guide: Who should submit a tax return?

If you do quality for self-assessment, the Which? tax calculator allows you to tot up your tax bill and submit your return direct to HMRC. Our video below explains how to use it. 

How do I get a UTR number?

Before you submit a tax return for the first time - say, after you've started a new business - you need to register for self-assessment with HMRC. When you do this, you will automatically be assigned a UTR number.

You can notify HMRC online, or fill in a form that can be printed and posted to HMRC.

When you register as a new business, you automatically register for self-assessment tax returns and Class 2 National Insurance at the same time. But you need to be quick - HMRC expects you to register within three months of commencing self-employment.

After you register for self-assessment, HMRC will post you an activation code (which can take up to 10 working days). You’ll be prompted for this when you first log in to your online tax account, also known as a Government Gateway account.

Information needed to register

As you'll be registering for self-assessment, you'll need the following:

  • Full name
  • Current address
  • National Insurance number
  • Date of birth
  • Phone number
  • Email address
  • The date you started being self-employed
  • Type of business
  • Business address
  • Business phone number

Your UTR questions answered

Below, we tackle commonly-asked questions about UTR numbers.


Do I have to pay to apply for a UTR number?


No, it's free to get a UTR number.


Where can I find my UTR number?


If you’ve already been issued with a UTR number, you can find it on a previous tax return and other documents you’ve received from HMRC, such as a notice to complete a tax return or a statement of account.

Your 10-digit number will may be called 'UTR', ‘tax reference’ or 'Official Use'.

When you complete an online tax return, your UTR appears on the second page (in ‘Tell us about you’), in a box below your last name and above your National Insurance number.

If you submit a paper tax return, your UTR appears on the first page, just above your National Insurance number.

You'll also find your UTR number on notices to file a return, payment reminders and in your HMRC online account


I've lost my UTR number. What do I do?


If you have already been issued with a UTR number but can’t find it, call HMRC’s self-assessment helpline (0300 200 3310). 

To help them find your UTR number, it's helpful if you have you National Insurance number to hand.

Submitting a tax return without your UTR number could result in a fine for not submitting a correct form by the deadline.


How do UTR numbers for business partnerships work?


If you're in a business partnership, you need a UTR number for the firm, as well as a UTR number for each partner in order to file online.

You'll need to submit a tax return for the firm, as well as one for your own income and expenses.


What are UTR numbers used for?


Your UTR number is what HMRC uses internally to track your tax obligations and match your records to your payments.

While some companies may accept a UTR as evidence that you are self-employed, you should note that UTRs are only proof that you have registered to submit a self-assessment tax return.


When will I need my UTR number?


You'll need your UTR number when completing a self-assessment tax return, and when working with an accountant or someone else helping you with your financial affairs.

HMRC will also ask for your UTR if you pre-pay your tax in instalments (known as payment on account).

Find out more: Paying tax as a self-employed person


How can I reactivate my UTR number?


If you stop submitting a self-assessment tax return, your UTR number will become dormant. 

When you start submitting tax returns again, it will automatically be reactivated.


What happens if I use the wrong UTR number?


Writing your UTR number down wrong is among the most common mistakes made on tax returns every year. 

Double check the number is correct before submitting your return. You may have to pay a fine if HMRC decide you have not shown enough care while filling out the forms.

If you realise you've submitted your return with the incorrect UTR, contact HMRC by phone or in writing to correct the error.