Find a lost UTR number

You’ll automatically be sent a Unique Taxpayer Reference (UTR) when you:

  • register for Self Assessment
  • set up a limited company

It’s a 10-digit number, sometimes with a letter ‘K’ on the end. It might just be called ‘tax reference’.

This guide is also available in Welsh (Cymraeg).

Where to find your UTR

Your UTR is on previous tax returns and other documents from HMRC, for example:

  • notices to file a return
  • payment reminders

You can also find your UTR in your HMRC online account.

If you can’t find your UTR

Call the Self Assessment helpline if you need your UTR and can’t find any documents from HMRC.