If you are self-employed, starting a business, or dealing with tax for the first time, you may hear people mention a UTR and wonder what it actually is. It sounds technical, but the idea is quite simple. A UTR is your Unique Taxpayer Reference. It is a 10-digit number that HMRC uses to identify you, or your business, for tax purposes. HMRC says you get one when you register for Self Assessment or when you set up a limited company. 

In everyday terms, your UTR helps HMRC match your tax records, returns and payments to the right person or business. Without it, dealing with tax can become much harder than it needs to be. It may also be called a tax reference on some HMRC documents. 

If you are sorting out self-employment, company registration or a tax return, this is one of those reference numbers you will want to keep somewhere safe. That is why firms such as Asmat & Co. Accountants often help clients with HMRC registration, Self Assessment and company tax matters as part of the wider compliance process.

The important thing to know is that you do not always apply for a UTR in the same way. It depends on whether you are registering as an individual for Self Assessment or setting up a limited company.

What is a UTR?

A UTR is a 10-digit number issued by HMRC. Its job is to identify a taxpayer within the UK tax system. HMRC states that individuals usually get a UTR when they register for Self Assessment, and limited companies get one when they are set up. 

Think of it as the tax equivalent of an account reference. It is how HMRC knows that a tax return, letter or payment belongs to you rather than somebody else.

A lot of people call it a “UTR number”, and that wording is very common in normal conversation. HMRC’s own design guidance prefers simply “UTR” or “Unique Taxpayer Reference”, but in practice most business owners and taxpayers will understand either term.

When do you need a UTR?

You generally need a UTR when you have to deal with HMRC through Self Assessment or Corporation Tax.

You are registering for Self Assessment

If you need to send a Self Assessment tax return, you will normally need a UTR. HMRC says you must tell them by 5 October following the end of the relevant tax year if you need to complete a tax return and have not sent one before, or if you registered before but did not need to send one for the previous year. 

This often applies if you are:

• Self-employed
• Receiving rental income
• A company director in situations where a tax return is required
• Receiving other untaxed income that needs to be declared

Asmat’s own site highlights self-employment, company directorship and rental income as common reasons a person may need to file a Self Assessment.

You have set up a limited company

If you form a private limited company, HMRC says you will usually be set up for Corporation Tax at the same time as registration, unless the company is dormant. You then receive a 10-digit UTR for the company.

This is important because your company’s UTR is separate from your personal UTR. If you are both a director and self-employed in some other capacity, you can end up with different tax references for different purposes.

You need to deal with HMRC about tax

You may need your UTR when:

• Filing a Self Assessment tax return
• Dealing with Corporation Tax for a limited company
• Speaking to HMRC about your tax affairs
• Checking or matching previous tax correspondence
• Working with an accountant on your return or company records

HMRC also says you can find your UTR on previous tax returns, notices to file, payment reminders and other documents they have sent you.

When might you not need one yet?

Not everyone needs a UTR straight away. For example, if you are employed under PAYE only and have no reason to complete a Self Assessment tax return, you may never need one as an individual.

Likewise, if you are only thinking about becoming self-employed but have not yet reached the point where you need to register with HMRC, you may not have a UTR yet. The number usually appears once you register for the relevant tax service. 

How do you get a UTR?

For Self Assessment

If you need a personal UTR, you usually get it by registering for a Self Assessment with HMRC. Once you register, HMRC says you will usually receive your UTR by post in around 15 days, although it can take longer if you live overseas.

That means it is wise not to leave registration until the last minute, especially if you know a deadline is coming up.

For a limited company

If you set up a limited company, HMRC says you are usually set up for Corporation Tax at the same time as incorporation, unless the company is dormant. Once your company receives its 10-digit UTR, you will need it to add Corporation Tax services to your business tax account. 

Where can you find your UTR if you lose it?

Losing your UTR is common, especially if you only use it once or twice a year. The good news is that HMRC gives several ways to find it.

If you are an individual or sole trader, HMRC says you can find your UTR:

• In your Personal Tax Account
• In the HMRC app
• On previous tax returns
• On notices to file a return
• On payment reminders and other HMRC documents 

If you are acting for an organisation such as a company, partnership or trust, HMRC says the organisation’s UTR can be found on previous tax returns and other HMRC documents. If you cannot find it online or in old paperwork, you can contact HMRC.

If you have a limited company, HMRC also says you can request your Corporation Tax UTR online, and it will be sent to the business address registered with Companies House.

Is a UTR the same as a company number?

No, and this is where many people get confused.

Your company registration number comes from Companies House when the company is formed. Your UTR comes from HMRC for tax purposes. They are not interchangeable. Companies House issues the certificate of incorporation and company number, while HMRC uses the UTR to identify the company for Corporation Tax. 

Why does your UTR matter?

Your UTR matters because it helps keep your tax records accurate. If you are filing returns, speaking to HMRC, or asking an accountant to help, the UTR is one of the key references used to access and process your tax information.

It also saves time. Instead of relying on name, address and date of birth every time, HMRC can use the UTR to locate the right record much more quickly.

Final thoughts

A UTR is simply your Unique Taxpayer Reference, a 10-digit tax reference used by HMRC. You will usually need one if you register for Self Assessment or set up a limited company. HMRC says it is normally issued after registration, and you can later find it through your online tax account, the HMRC app, or previous HMRC letters and returns. 

If you are unsure whether you need a UTR yet, the best question to ask is whether you need to register with HMRC for Self Assessment or Corporation Tax. If the answer is yes, your UTR will become an important part of your tax setup.

Last Updated on April 7, 2026