UTR Number: How to Get One, Find Yours and How Long It Takes

You need a UTR to file a Self Assessment tax return, and often to register with accountants, platforms and some clients. It's free, it doesn't change, and you only ever get one for your personal tax. Here's how to get a UTR for the first time and how to find one you've misplaced.

What a UTR number looks like

It's 10 digits, and HMRC letters may simply call it your "tax reference". Don't confuse it with your National Insurance number, which has letters, or an employer PAYE reference. Companies have their own separate UTR for Corporation Tax.

How to get a UTR for the first time

1. Register for Self Assessment on GOV.UK, as self-employed, a landlord or for other income.
2. HMRC sets up your record and posts your UTR.
3. Expect it around 15 days after registering, longer if you live abroad.
4. Once it arrives, set up your online account so you can file.

You register for Self Assessment rather than applying for a UTR on its own: the UTR comes as part of registering.

The 5 October deadline

If you need to file a tax return for the previous tax year, GOV.UK says you must tell HMRC by 5 October. For the 2025 to 2026 tax year, that deadline was 5 October, just after the tax year's end in April. Tell HMRC later and you could get a penalty. If you started a side hustle or self-employment during a tax year, register by the following 5 October, and don't wait for the money to build up.

How to find a lost UTR

Where to look	What you'll see
The HMRC app	Your Self Assessment UTR and how much tax you owe
Your Personal Tax Account online	Your UTR in your Self Assessment details
Old tax returns	The UTR on the return itself
HMRC letters	Notices to file a return and payment reminders

The HMRC app is usually the fastest. If you can't find your UTR anywhere, GOV.UK says to contact HMRC.

Registered before but stopped filing?

If you registered for Self Assessment in the past and later didn't need to send returns, you keep the same UTR. GOV.UK says you may need to reactivate your Self Assessment account rather than register from scratch. That matters, because registering again as if you were new can create duplicate records and delays.

Waiting too long for your UTR

If it's been more than the usual 15 days, check HMRC's guidance on when you can expect a reply, and allow longer if you live overseas. Delays can make the filing deadline tight, so register early rather than in January.

UTRs for companies

A limited company has its own Corporation Tax UTR, separate from yours. GOV.UK says you can request it online and HMRC will post it to the business address registered with Companies House. Directors who also file personal Self Assessment will have both: one for themselves, one for the company.

Do you need a UTR for a side hustle?

Not always. If your self-employment income is covered by the 1,000 pound trading allowance and you have no other reason to file, you may not need to register at all. But GOV.UK says you need a Self Assessment return if you have more than 2,500 pounds of other untaxed income, such as tips or rent, and many people need to file once their side income passes the trading allowance. If you're unsure, check GOV.UK's guidance on whether you need to send a tax return before the 5 October deadline, rather than after it.

If HMRC sends a notice to file

Sometimes the first time people see their UTR is on a notice to file a return. That letter carries the UTR, so keep it. If you get one and don't think you need to file, don't ignore it: tell HMRC, which you can do in the HMRC app, so the record is closed and you're not chased for a return.

UTR vs National Insurance number vs tax code

Number	What it's for	Where you'll see it
UTR	Your Self Assessment record	HMRC app, Personal Tax Account, HMRC letters
National Insurance number	Your National Insurance record and pension	HMRC app, payslips
Tax code	How much tax your employer deducts under PAYE	Payslips, HMRC app

Who'll ask you for your UTR

• Your accountant, so they can act for you with HMRC.
• Some clients and platforms that need your tax details.
• HMRC itself, when you call about your tax.

Treat it like other personal tax details: share it with people who need it for your tax, and don't post it publicly.

My verdict

Register for Self Assessment as soon as you know you'll need a return, and well before 5 October. Download the HMRC app while you wait, because once your UTR is issued it's the easiest place to find it. If you're setting up as self-employed, sole trader vs limited company is worth reading first, and if you're earning from content, Substack in the UK covers the tax side for writers.

Frequently asked questions

What is a UTR number?

A 10-digit Unique Taxpayer Reference HMRC gives you when you register for Self Assessment.

How long does it take to get a UTR?

Usually around 15 days after you register, longer if you live overseas.

Where can I find my UTR number?

In the HMRC app, your Personal Tax Account, old tax returns and HMRC letters like notices to file or payment reminders.

When do I need to register for a UTR?

By 5 October after the end of the tax year you need to file a return for, or you could get a penalty.

Does a limited company have a different UTR?

Yes. A company has its own Corporation Tax UTR, which you can request online.