Last updated: October 2026
To get a UTR number, you register for Self Assessment with HMRC. You can register online through GOV.UK. HMRC then posts your ten-digit Unique Taxpayer Reference (UTR) to your address, usually within 10 working days, though you should allow up to 15. If you live abroad, allow around 21 days.
This guide explains how to get a UTR number step by step, who needs one, how long it takes and how to find a lost UTR.
Quick Answer: Getting Your UTR
| Step | What happens | Timing |
|---|---|---|
| 1. Register for Self Assessment | Complete the online form on GOV.UK | 15 to 30 minutes |
| 2. HMRC processes your registration | HMRC creates your Self Assessment record | A few days |
| 3. UTR arrives by post | Your ten-digit UTR comes in a letter | Usually 10, up to 15 working days (21 if abroad) |
| 4. Activation code arrives | A separate letter lets you file online | Within a few working days |
What Is a UTR Number?
A UTR (Unique Taxpayer Reference) is a ten-digit number that HMRC gives every person and business registered for Self Assessment. It identifies your tax record for life and never changes, even if your circumstances do.
Every UTR is exactly ten digits, for example 1234567890. When you pay Self Assessment tax, you add the letter K to the end of your UTR as your payment reference, for example 1234567890K.
UTR vs National Insurance Number
| UTR | National Insurance number | |
|---|---|---|
| Format | 10 digits | 2 letters, 6 numbers, 1 letter |
| Used for | Self Assessment and Corporation Tax | National Insurance, State Pension and benefits |
| How you get it | Register for Self Assessment | Issued automatically before age 16 |
| Does everyone have one? | No, only people who register | Yes, everyone with the right to work |
One number cannot replace the other. Many people have a National Insurance number but never need a UTR.
Who Needs a UTR Number?
You need a UTR if you must file a Self Assessment tax return. This usually includes:
- Sole traders and self-employed people with income over £1,000
- Partners in a business partnership
- Company directors with untaxed income, such as dividends of £10,000 or more
- Landlords with rental income above the reporting limits
- CIS subcontractors, who also need a UTR to register under the Construction Industry Scheme
- Anyone with untaxed savings, investment or foreign income above the limits
Not sure if this applies to you? Our guide on whether you need to file a Self Assessment tax return sets out every threshold.
A limited company gets its own, separate UTR automatically after it registers at Companies House. HMRC posts this to the company’s registered office. It is different from each director’s personal UTR. Our checklist for newly formed companies explains what to do with it.
How to Get a UTR Number: Step by Step
Step 1: Choose the Right Registration Route
HMRC uses a different route depending on why you need to file:
- Self-employed or sole trader: register as self-employed online.
- Not self-employed: for example a landlord or company director, use form SA1.
- Partner in a partnership: use form SA401.
- The partnership itself: use form SA400 to get a UTR for the partnership return.
Step 2: Sign In to Your HMRC Account
Sign in with Government Gateway or GOV.UK One Login. If you do not have an account, you can create one during registration. You can start on HMRC’s Register for Self Assessment page.
Step 3: Complete the Form
You will need:
- Your National Insurance number
- Your name, date of birth and address
- Your phone number and email address
- The date you started self-employment or the date your other income began
- A short description of your business or income
Step 4: Wait for Your UTR and Activation Code
HMRC posts your UTR in a letter. If you registered online, you may also see your UTR in the HMRC app before the letter arrives. A separate letter brings an activation code, which you need before you can file online. Use it promptly, because it expires.
How Long Does It Take to Get a UTR Number?
HMRC usually posts your UTR within 10 working days, but you should allow up to 15. If you live abroad, allow around 21 days. HMRC does not send UTRs by email.
Register well before the deadline. For the 2025/26 tax year, the registration deadline was 5 October 2026, and the online filing deadline is 31 January 2027. Our Self Assessment deadlines guide lists every date. If you register in late January, your UTR may not arrive in time, and HMRC will still charge a late filing penalty.
Where Do You Use Your UTR?
- Filing your Self Assessment tax return each year
- Paying Self Assessment tax, including payments on account
- Registering as a CIS subcontractor, so contractors deduct 20% rather than 30%
- Authorising an accountant to act for you
- Any letter or call to HMRC about your Self Assessment record
How Do I Find a Lost UTR Number?
Check these places first:
- The HMRC app: the quickest way to see your UTR.
- Your Personal Tax Account: on GOV.UK, once you sign in.
- Your welcome letter: the SA250 letter HMRC sent when you first registered.
- Past tax returns, statements or payment reminders: your UTR appears on all of them.
If none of these work, contact HMRC. They can post your UTR to you after confirming your identity. For security, HMRC never gives out a UTR by email.
Is There a UTR Checker?
HMRC does not offer a public UTR checker. You cannot look up someone else’s UTR online, so be careful of websites that claim to do this.
To check your own UTR, use the HMRC app, your Personal Tax Account or any HMRC letter about your Self Assessment.
If you run a construction business, you can verify a subcontractor’s UTR through HMRC’s CIS verification service before you pay them. This confirms the subcontractor is registered and tells you the right rate of deduction.
A limited company’s UTR is also private. You will find it on the letter HMRC sends after incorporation, not on the Companies House register.
Let Us Handle It For You
Registering for the first time can feel confusing, especially if you have more than one type of income. Our Self Assessment accountants in Slough can register you, get your UTR and file your first return before the 31 January deadline.
Frequently Asked Questions
Is it free to get a UTR number?
Yes. Registering for Self Assessment with HMRC is free. Be wary of websites that charge a fee just to apply for a UTR.
Can I start trading before I get my UTR?
Yes. You can start trading straight away. You must still register by 5 October after the end of the tax year in which you started.
Does my UTR ever change?
No. Your UTR stays the same for life, even if you move house or change your business.
Do I need a new UTR if I stop and restart self-employment?
No. You keep your original UTR. When you restart, tell HMRC and it will reactivate your record.
Is my company UTR the same as my personal UTR?
No. A limited company has its own UTR for Corporation Tax. Directors who file Self Assessment have a separate personal UTR.
Can HMRC tell me my UTR over the phone?
For security, HMRC usually posts your UTR to the address it holds for you, rather than reading it out on the phone. The fastest way to see it is through the HMRC app or your Personal Tax Account.