Submitting a Self Assessment tax return can be a headache. But, if you’re self-employed, a partner in a partnership business, a minister of religion or a trustee or the executor of an estate, you will need to inform HM Revenue and Customs (HMRC) of your income each year, in order to pay the right amount of Income Tax.

You may also need to complete a tax return if you’re a company director with income that’s not taxed under Pay As You Earn (PAYE), you have untaxed income, you receive income from a trust, settlement or the estate of a deceased person, you have foreign income, you have income from savings and investments over a certain amount or you earn £100,000 or more before tax. This list isn’t exhaustive, though, and HMRC may require you to submit a Self Assessment tax return for various other reasons too.

In order to complete your tax return, you’ll need a Unique Taxpayer Reference (UTR) number. You’ll also need your UTR number if you’re working with an accountant or other financial aide, and HMRC will ask you for it if you pre-pay your tax in instalments — known as payments on account.

Once you register for Self Assessment — either online or by post — HMRC will assign you a UTR number. 

Your UTR number will then be sent to you by secure post, but you can also request it by speaking to HMRC on the phone or by sending them a letter. Alternatively, you can log in to your online account, where it will be displayed in the top right corner of your online account summary.

In this article, we’ll take you through exactly how to apply for a UTR number, but first, you might find it helpful to know what a UTR number is, why you need one and what it’s used for.

Also called a ‘tax reference number’, a UTR number is a code that HMRC uses internally to identify individual Self Assessment taxpayers.

UTR numbers can be found on Self Assessment forms like tax returns and statements. They are made up of ten digits and sometimes contain a letter. Typically, this will be the letter ‘K’ at the end.

Each taxpayer is assigned a different number so their tax obligations can be tracked and records can be matched to payments.

Once you are assigned a UTR number, you keep it for the rest of your life, as you do with your National Insurance number.

As already mentioned, you’ll need your UTR number in order to submit a Self Assessment tax return, so if you want to work for yourself, you must apply for one.

In some instances, you may be able to use your UTR as evidence of your self-employment, but take note that it really only proves that you have registered for Self Assessment.

To register for Self Assessment and be issued a UTR number, you will need to provide the following information:

  • Your full name and date of birth
  • Your National Insurance number
  • Your contact details including your current address, phone number and email address

If you own a business, you might also need to provide details like:

  • The date you started working for yourself
  • The type of business you run
  • Your company address
  • Your company phone number

The quickest and easiest way to apply for a UTR number is to register for Self Assessment online. HMRC expects you to do this within three months of starting your business. Note that there are different ways to register, depending on whether you’re self-employed, not self-employed or registering a partner or partnership.

Follow these steps to retrieve your UTR number:

  1. Register for Self Assessment by filling in the relevant form according to your employment status.
  2. Once you’ve created an account, you should receive your UTR number through the post. If not, you can log in to your account using your activation code, if it’s the first time you’ve done this, your Government Gateway User ID and password. (Note that you must sign in within 28 days of receiving your activation code, otherwise, you will have to submit a new form.)
  3. Once you’ve signed in, you will find your UTR number in the top right corner of your online account summary.

If you would prefer to speak to someone, you can call HMRC on 0300 200 3310 to request your UTR number.

In order to verify your identity, they may ask you to provide information like your personal details and National Insurance number.

They will then either post your UTR number within seven working days or advise you on how to apply for your UTR number online.

Another way to request your UTR number is to send HMRC a letter to: Pay As You Earn and Self Assessment, HM Revenue and Customs, BX9 1AS.

This method isn’t advisable if you need to file a tax return quickly, though, as it takes much longer.

Once you’ve registered for Self Assessment, you should receive your UTR number in the post within 10 working days (or 21 days if you are abroad). 

However, it can take up to six weeks to receive it, so if you are submitting a tax return for the first time, make sure you register with HMRC before 20th December to avoid having to pay penalties. This is because HMRC must receive your tax return and any money you owe by midnight on 31st January.

Your 10-digit number will be labelled “UTR”, “Tax Reference” or “Official Use” and can be found in the following ways:

  • On any letters from HMRC, such as those reminding you to submit your Self Assessment tax return or your statement of accounts
  • On your last tax return documents
  • On your SA250 (this is the letter issued to you by HMRC when you first registered for Self Assessment)
  • By logging in to your Government Gateway account, where you will see it on your online account summary
  • By calling HMRC on 0300 200 3310

If you own a limited company, you will need to request your Corporation Tax UTR number online, and HMRC will send it to the registered business address.

When you submit a Self Assessment tax return, you will be asked to provide your UTR number. If you’re filling in an online return, you’ll need to enter it on the second page, in the “Tell us about you” section, in a box in between your surname and National Insurance number. If you’re filling in a paper return, you’ll need to enter your UTR number on the first page, just above your National Insurance number. 

If you leave this box blank, HMRC will reject your return, and if you miss the submission deadline, you could face fines and penalties of up to £1,600.

If you’re self-employed, a partner in a partnership business, a minister of religion or a trustee or the executor of an estate, you will need to submit a Self Assessment tax return each year. 

In order to complete your tax return, you’ll need a Unique Taxpayer Reference (UTR) number. You can apply for this by registering for Self Assessment — either online or by post. HMRC will then send you your UTR number by secure post, but you can also request it by speaking to them over the phone or by sending them a letter. Alternatively, you can log in to your online account, where it will be displayed in the top right corner of your online account summary.

A UTR number is a ten-digit code that HMRC uses internally to identify individual Self Assessment taxpayers. Each taxpayer is assigned a different number so their tax obligations can be tracked and records can be matched to payments.

To register for Self Assessment and be issued a UTR number, you will need to provide your full name and date of birth, National Insurance number and contact details, including your current address, phone number and email address. If you own a business, you might also need to provide details like the date you started working for yourself, the type of business you run, your company address and your company phone number.

To apply for a UTR number online, you need to register for Self Assessment on the government’s website.  You’ll then receive your code in the post, or you can find it by logging in to your account. 

You can apply for a UTR number over the phone, by calling HMRC who will then post your UTR number within seven working days.

Another way to request your UTR number is to send HMRC a letter, however, this method takes much longer.

Once you’ve registered for Self Assessment, you should receive your UTR number in the post within 10 working days, but it can take up to six weeks to arrive.

Your 10-digit number will be labelled “UTR”, “Tax Reference” or “Official Use” and can be found on any letters from HMRC, on your last tax return documents, on your SA250, by logging into your Government Gateway account or by calling HMRC.

If you fail to include your UTR number on your Self Assessment tax return, you could face having to pay a fine of up to £1,600.