The UTR or unique taxpayer reference number is the series of digits that identifies you to HMRC. As a self-employed person, it’s the number that identifies you as an individual company. You will automatically be registered with a UTR number when you set yourself up for Self Assessment tax returns or when you set up a limited company.
You'll need a UTR number from HMRC in order to fill out your self-assessment tax return each year and to communicate with HMRC for any other reasons.
If you lost it, you can find it in several places:
- On the SA250 form you received when you registered as self-employed
- On a previous Self Assessment tax return
- On your first communication from HMRC if you incorporated a limited company
- On a notice to file
- On a payment reminder from HMRC.