Unique Taxpayer Reference (UTR) Guide
⚡ Quick Answer: A UTR (Unique Taxpayer Reference) is a 10-digit number HMRC assigns to every UK taxpayer. You need it to file Self Assessment tax returns. If HMRC sends your UTR letter to your Hoxton Mix address, it will be scanned and available under the Mail tab in your portal on the day it arrives.
What Is a UTR Number?
A UTR is a unique 10-digit code used by HMRC to identify you for tax purposes. There are two types:
Type | Who gets it | When it's issued |
|---|---|---|
Personal UTR | Self-employed individuals, company directors | When you register for Self Assessment |
Company UTR | Limited companies | When the company is registered with HMRC (shown on CT603 form) |
Company directors have their own personal UTR in addition to their company's corporate UTR.
Where to Find Your UTR
Source | Details |
|---|---|
SA250 letter | The "Welcome to Self Assessment" letter from HMRC |
Previous tax returns | Listed on any Self Assessment return you've filed |
HMRC correspondence | Payment reminders, notices to file, statements of account |
HMRC online | Log in to your personal tax account or use the HMRC app |
CT603 form | For company UTRs — sent after company registration |
How to Get a UTR
You must register within 3 months of starting your business.
Method | How |
|---|---|
Online | Register as self-employed on the HMRC website |
Phone | Call HMRC on 0300 200 3310 (have your National Insurance number ready) |
What you'll need to register
- Full name, date of birth, and address
- National Insurance number
- Contact details
- Self-employment start date
- Business details (address and type)
After registering, HMRC will send an activation code by post. Use it to set up your online tax account.
UTR Letters Sent to Your Hoxton Mix Address
If HMRC sends your UTR letter to your virtual office address, it will be scanned on the day it arrives and available under the Mail tab in your customer portal. You'll receive a notification when it's ready.
Haven't received it yet?
- If the letter doesn't appear in your portal, it usually means it hasn't arrived or is still being processed
- If you have multiple companies, this doesn't affect processing — letters are matched by company name or director name
- If your subscription has ended, mail received after cancellation may be returned to sender. Contact HMRC directly to request a replacement
💡 Tip: If your subscription is inactive and you're expecting a UTR letter, reactivate your account first or contact HMRC to send it to an alternative address.
Common Questions
What if I've lost my UTR number?
Check all HMRC correspondence — tax returns, payment reminders, your SA250 letter. If you can't find it, call HMRC on 0300 200 3310.
Do I need a UTR to file a tax return?
Yes. You cannot submit a Self Assessment return without a UTR.
Do company directors have UTR numbers?
Yes. Directors have a personal UTR for their individual tax affairs, separate from the company's corporate UTR.
How long does it take to receive a UTR?
HMRC typically sends your UTR by post within 10 working days of registration. The activation code for your online account follows separately.
Updated on: 28/03/2026