You’re trying to file your Self Assessment return, and you’ve hit a wall: you can’t find your UTR number. Without it, you can’t file. And the deadline is getting closer.

Don’t panic. Your UTR doesn’t disappear — it’s permanently assigned to you. It’s just a matter of tracking it down. Here’s every way to find it, from fastest to slowest.

What Is a UTR Number?

Your UTR (Unique Taxpayer Reference) is a 10-digit number that HMRC assigns to you when you register for Self Assessment. It stays the same for life — you keep the same UTR whether you file every year or skip a few years.

According to HMRC’s guidance on UTR numbers, you need your UTR to:

  • File your Self Assessment tax return (online or on paper)
  • Pay your Self Assessment tax bill (it’s the payment reference)
  • Communicate with HMRC about your tax affairs
  • Set up a payment plan or appeal a penalty

Your UTR is different from your National Insurance number (which is 9 characters: 2 letters, 6 numbers, 1 letter). You need both to file your Self Assessment.

Where to Find Your UTR: The Quick Checklist

Before contacting HMRC, check these places — your UTR is probably in one of them:

1. Previous tax returns

If you’ve filed a Self Assessment return before, your UTR is printed on the return itself, on the tax calculation summary, and on any HMRC correspondence about your return. Check your files, emails, or accounting software.

2. HMRC letters

HMRC sends several letters that include your UTR:

  • SA250 — the welcome letter you received when you first registered for Self Assessment
  • SA302 — your tax calculation (sent after you file)
  • Statement of Account — shows your tax position
  • Penalty notices — if you’ve been penalised for late filing, the notice includes your UTR
  • Payment reminders — HMRC sends these in January

3. Your Government Gateway account

If you’ve set up a Government Gateway account (which you need to file online), your UTR is displayed in your Self Assessment section.

  1. Go to HMRC Online
  2. Log in with your Government Gateway credentials
  3. Go to Self Assessment
  4. Your UTR is displayed on the main Self Assessment page

4. Your accountant or tax agent

If you’ve used an accountant or filing service in the past, they’ll have your UTR on file. Contact them — they can usually provide it immediately.

5. Your payslip or P60

If you’re an employee as well as self-employed, your UTR may appear on your P60 or payslip if your employer uses it for tax code adjustments. This is less common but worth checking.

6. Your banking app

If you’ve paid a Self Assessment tax bill before, search your bank transactions for “HMRC” or “Self Assessment.” Your UTR is used as the payment reference for bank transfers. It’ll show up in the transaction details.

What If You Still Can’t Find It?

If you’ve checked everywhere and still can’t find your UTR, you need to contact HMRC directly.

Option 1: Call HMRC (fastest)

Call the Self Assessment helpline on 0300 200 3310 (Monday to Friday, 8am to 6pm).

Have ready:

  • Your National Insurance number
  • Your full name and date of birth
  • Your address (must match what HMRC has on file)

HMRC will verify your identity and then:

  • Post your UTR to your registered address — this takes up to 10 working days
  • In some cases, they may confirm it over the phone, but this is at the advisor’s discretion and depends on the security checks you pass

Important: HMRC cannot email your UTR for security reasons. It must be sent by post to your registered address. If you’ve moved house and haven’t updated your address with HMRC, this will cause delays — update your address first.

Option 2: Use HMRC’s online recovery tool

HMRC has an online tool to recover lost UTR numbers. You’ll need to enter personal details to verify your identity, and HMRC will post the UTR to your registered address within 10 working days.

Option 3: Write to HMRC

If you prefer, you can write to HMRC at:

Self Assessment HM Revenue and Customs BX9 1AS United Kingdom

Include your National Insurance number, full name, date of birth, and current address. This is the slowest option — allow at least 4 weeks for a response.

What If You’ve Never Had a UTR?

If you’ve never registered for Self Assessment before, you don’t have a UTR yet. You need to register first.

How to register

  1. Go to HMRC’s registration page
  2. You’ll need your National Insurance number
  3. Fill in the online form with your personal details and the date you started self-employment (or became a landlord)
  4. HMRC will send you a UTR number by post within 10 working days
  5. You’ll also receive an activation code for your Government Gateway account (sent separately, also by post)

The timing problem

If you’re reading this in January and the deadline is days away, registering now means your UTR won’t arrive in time. Here’s what to do:

  1. Register immediately — start the process today
  2. File as soon as your UTR arrives — even if it’s after 31 January
  3. Appeal the late filing penalty — explain that you registered as soon as you realised you needed to file, but HMRC’s postal delivery took longer than expected. This can be a valid reasonable excuse. See our appeal guide for the process.
  4. Keep evidence — screenshot your registration confirmation, note the date, and keep the envelope your UTR arrives in (it shows the postmark date)

According to HMRC’s registration guidance, you should register by 5 October after the end of the tax year in which you became self-employed. If you missed this deadline, register now — late registration is better than no registration.

What If Your UTR Is Linked to an Old Address?

If you’ve moved house and your UTR is being sent to your old address, you need to update your address with HMRC first.

  1. Update your address online — log into your Government Gateway account and update your contact details
  2. Or call HMRC on 0300 200 3310 and provide your new address
  3. Wait for confirmation that your address has been updated
  4. Then request your UTR — it’ll be sent to your new address

If you don’t have a Government Gateway account and can’t verify your identity online, you’ll need to call HMRC. Be prepared for security questions — they’ll ask about your previous addresses, employment history, and other details to verify who you are.

Can You File Without a UTR?

No. Your UTR is a mandatory field on the Self Assessment return. The online filing system won’t let you submit without it. Paper returns also require it.

If the deadline is approaching and you don’t have your UTR:

  1. Request it immediately — call 0300 200 3310
  2. File as soon as it arrives — even if it’s late
  3. Appeal the penalty — postal delay in receiving your UTR can be a reasonable excuse

See our missed deadline guide for what to do if you end up filing after 31 January.

UTR vs Other Tax Reference Numbers: Don’t Confuse Them

Number Format What it’s for
UTR 10 digits (e.g., 1234567890) Self Assessment tax returns
National Insurance number 2 letters + 6 digits + 1 letter (e.g., AB123456C) NI contributions, benefits, employment
Employer PAYE reference 3 digits + slash + letters/numbers (e.g., 123/AB456) Your employer’s tax scheme (on your P60)
VAT number 9 digits (sometimes with GB prefix) VAT registration (if you’re VAT-registered)
Corporation Tax UTR 10 digits (different from SA UTR) Limited company tax returns

If you’re self-employed and also run a limited company, you’ll have two different UTRs — one for your personal Self Assessment and one for the company’s Corporation Tax. Make sure you’re using the right one.

How to Avoid Losing Your UTR Again

Once you’ve found your UTR, take these steps so you never have to search for it again:

  1. Save it securely — store it in a password manager, a locked notes app, or a physical file with your tax documents
  2. Note it on your tax return — once you file, your UTR is on the return and the tax calculation
  3. Set up a Government Gateway account — your UTR is always visible there
  4. Keep HMRC letters — any letter from HMRC about Self Assessment will include your UTR
  5. Tell your accountant — if you use one, make sure they have it on file
  6. Update your address — if you move, update HMRC immediately so future correspondence reaches you

The Bottom Line

Losing your UTR is frustrating but fixable. Here’s the quick action plan:

  1. Check your documents first — previous returns, HMRC letters, Government Gateway account, bank transactions
  2. If you can’t find it, call HMRC on 0300 200 3310 — they’ll post it to you (up to 10 working days)
  3. If you’ve never had one, register for Self Assessment — at gov.uk
  4. If the deadline is looming, register/request now and file when it arrives — then appeal any late penalty
  5. Once you have it, save it somewhere secure — so you never have to do this again

The 10-day postal wait is the biggest frustration. The sooner you start the process, the sooner you’ll have your UTR and can file.

If you’ve missed the deadline because you couldn’t find your UTR, see our guide on what to do when you miss the Self Assessment deadline. If you’ve received a penalty and want to appeal, see how to appeal an HMRC penalty. For the full breakdown of late penalties, see what happens when you file late.

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