How to Apply for a UTR Number

utr number


Applying for a UTR number forms an essential part of the self assessment process.

If you come under the self assessment rules, but fail to register and file a tax return, you risk financial penalties.

In this guide, we answer frequently asked questions about UTR numbers, including how to apply for a UTR number to ensure you are able to submit your self assessment tax return on time.


What is a UTR number?

A UTR number, which stands for “Unique Taxpayer Reference”, is the number assigned to you by HMRC when you register for self assessment for the purpose of paying Income Tax and National Insurance contributions (NICs). This is a 10-digit number – often with the letter ‘K’ at the end – that is used to identify you as a UK taxpayer. This will enable you to file your self assessment tax return, and to pay any Income Tax and NICs due.


Who needs a UTR number?

Anyone who is required to file a self assessment tax return with HMRC will need to have a UTR number, where neither an online or postal return can be submitted without one.

Anyone who has earned more than £1,000 from self-employment during the last tax year would need to declare this income by way of self assessment, paying tax and class 2 NICs, after the end of the tax year that it applies to. This could be anyone working on a self-employed basis, such as a sole trader, a business partner or small business owner.

It could also be someone in paid employment but who, in addition to their salary on which they pay tax through PAYE, is in receipt of other or multiple sources of income. This income could include rental income, interest earned on savings or share dividends, where the individual would be required to declare this income and pay tax on it via self assessment.


When is a UTR number needed by?

You can file your tax return online or by post, although the time for submitting your return will be extended by using the online system. If you are filing by post, you must submit your tax return by midnight on 31 October of the same year in which the income was earned. When filing online, this time is extended to midnight on 31 January of the following year.

If you are a filing a tax return for the first time as someone self-employed, you must first register for self assessment with HMRC. You will need to do this by 5 October in the second tax year that your business has been running. Depending on whether you plan to file your self assessment tax return online or by post, you will need to have registered for self assessment and obtained your UTR number in advance of the relevant deadline date.

If you are submitting a paper return, you will also need to request a paper copy of the main self assessment tax return (Form SA100) by calling HMRC. Again, you will need to do this in advance of the relevant deadline date for filing your self assessment by post. You can download all other supplementary pages to the main tax return online. These can then be printed off and completed manually, to be posted together with your Form SA100.

There are various supplementary pages that may need to be completed, depending on your circumstances. These include the SA103S or SA103F supplementary pages for self-employment, the SA104S or SA104F supplementary pages for business partnerships, and the SA102 supplementary pages for employees or company directors.


How do you get a UTR number?

If you have to send a tax return and you have not sent one before, you must register for self assessment, where your UTR number will be assigned to you automatically by HMRC once you have registered. Once you get a UTR number, this will usually stay with you for life.

You can register for self assessment either online or by post. Having successfully registered for self assessment, HMRC should post you out your 10-digit UTR number. This could take anything between 10 to 15 workings day, depending on how you register.

There is a useful online tool at GOV.UK (using the search term ‘Register for Self Assessment’) to help determine if you need to register for self assessment and obtain a UTR number based on your circumstances. When using the online tool, you will be asked a number of questions to help identify whether or not you need to register for self assessment. If you are self-employed, these questions will include:

  • Have you filed a tax return before? YES/NO
  • Did you work for yourself between 6 April 2022 and 5 April 2023? YES/NO (where you may have worked for yourself as a sole trader, business partner or director of a limited company, even if you had another job as well)
  • What was your work status when you worked for yourself? Self-employed as a sole trader/Partner in a business partnership/Director of a limited company
  • Did you earn more than £1,000 working for yourself in the last tax year? YES/NO (where the last tax year started on 6 April 2022 and ended on 5 April 2023).

For example, if you have not filed a tax return before, but worked for yourself as a sole trader between 6 April 2022 and 5 April 2023, earning more than £1,000, you must register with HMRC for self assessment. You must tell HMRC by 5 October if you need to complete a tax return and have not sent one before, where you could be fined if you do not.

If you earned less than £1,000, you will not be required to file a tax return. This is because there is a £1,000 tax-free trading allowance for those working on a self-employed basis.


How do taxpayers apply for UTR numbers online?

To obtain a UTR number, you will first need to register for self assessment.

If you are happy to register online, you can use the link at the bottom of the page ‘Register for Self Assessment’, having completed the online questionnaire.

To register for self assessment online, you must create an online tax account. You will need a Government Gateway user ID and password to be able to sign in. If you do not have a user ID, you will be able to create one by proving you identity. To do this, you will need your National Insurance number or postcode, plus two of the following:

  • a valid UK passport
  • a DVLA issued photo card driving licence
  • a payslip from the last 3 months or P60 for the last tax year
  • details of a tax credit claim, if you have made one
  • details from a self assessment tax return, if you have made one (which will not be the case if you do not yet have a UTR number)
  • information held on your credit record, such as loans, credit cards or mortgages.

You should get your UTR number by post after you register, together with a separate letter with a code to activate your online account, although you can usually see your UTR sooner in your online personal tax account or on the HMRC app if you have downloaded this on a mobile device. Having downloaded and opened the app, you will need your Government Gateway user ID and password to sign in for the first time. If you do not yet have a user ID, you can create one using the app. You will then be able to subsequently sign into the app using either a 6-digit PIN, your fingerprint or facial recognition technology.


How do taxpayers apply for UTR numbers by post?

If you cannot register for self assessment using the online service, you must instead fill in Form CWF1. You can search for this online and complete it on-screen, before printing this out and posting it to HMRC using the postal address as shown on the form. You will need to have all your information ready as you cannot save a partly completed form, including your National Insurance number, where you cannot register for self assessment without this.

If you have previously filed tax returns by post, you may want to create on online account using your UTR number which can be found on any tax returns or documents from HMRC. Once you have registered to use the online service, you will be sent an activation code. You can also reactivate an existing online account for self assessment using Form CWF1, for which again you will need your UTR number from when you registered before.


How do taxpayers other than the self-employed apply for UTR numbers?

How you register for self assessment all depends on your circumstances.

If you either want to register a new partnership as the “nominated partner”, register as a partner having recently joined an existing partnership, or register as a director in receipt of untaxed income, such as share dividends, there are different forms that must be used. These are Form SA400, Form SA401 and Form SA1 respectively. You can again use the online service to submit your form, or fill in the form on-screen to print and post instead.

To register for self assessment for any reason other than self-employment, you must again use Form SA1. You can fill in and send Form SA1 online, or complete this online before printing it out and posting it to HMRC. If you are not self-employed, you may still need to register for self assessment for any one of the following reasons:

  • If you receive income from land and property in the UK
  • If you have taxable foreign income
  • If you have adjusted net income over £50,000, and you or your partner carry on receiving Child Benefit payments
  • If you have yearly income over £100,000
  • If you receive yearly income from a trust or settlement
  • If you get untaxed income that cannot be collected through your PAYE tax code
  • If you have Capital Gains Tax to pay.


How do you use your UTR number?

When using the online service to complete your self assessment, both your UTR number and National Insurance number should be automatically generated in the corresponding boxes of the online form. If you are submitting your return by post, you will need to insert your UTR and National Insurance number in the boxes at the top of the form yourself.

In addition to completing your return, the online service will allow you to view previous returns, check your details, and print out your self assessment tax calculation. However, not everyone can use the online service and some will now need to use alternative software, for example, if you were not living in the UK in the tax year (non resident) or you claim the remittance basis. The remittance basis is an alternative tax treatment available to those who are a resident in the UK, but not UK domiciled, and have foreign income and gains.


Where can you find your UTR number?

Having been assigned a UTR number, you can find this:

  • in your online tax account
  • in the HMRC app, or
  • on previous tax returns and other documentation from HMRC, for example, notices to file a return or payment reminders, or any letters about your self assessment.

Your UTR number might just be called ‘tax reference’. If you cannot find your UTR number online or in any correspondence, you can request this by calling HMRC’s self assessment helpline. HMRC will post your UTR number out to you within around 10 days. This means that if you have been unable to locate your UTR, where the deadline for filing your tax return is pending, you will need to contact HMRC as soon as possible to make this request.


UTR number FAQs

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Legal disclaimer

The matters contained in this article are intended to be for general information purposes only. This article does not constitute legal or financial advice, nor is it a complete or authoritative statement of the law or tax rules and should not be treated as such.

Whilst every effort is made to ensure that the information is correct, no warranty, express or implied, is given as to its accuracy and no liability is accepted for any error or omission.

Before acting on any of the information contained herein, expert professional advice should be sought.


Gill Laing is a qualified Legal Researcher & Analyst with niche specialisms in Law, Tax, Human Resources, Immigration & Employment Law.

Gill is a Multiple Business Owner and the Managing Director of Prof Services Limited - a Marketing & Content Agency for the Professional Services Sector.

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