What is a UTR number?

New business owners in the UK frequently encounter references to a UTR number when dealing with HMRC — particularly when registering for Self Assessment or filing a tax return for the first time. Understanding what this number is, how to obtain it, and when you will need it is one of the early administrative steps for most founders.

A Unique Taxpayer Reference (UTR) is a reference number assigned by HMRC to identify you or your business for tax purposes. Sole traders receive a UTR when they register for Self Assessment. Limited companies also receive a UTR when they register with Companies House and notify HMRC. Your UTR appears on correspondence from HMRC and is required whenever you file a tax return, contact HMRC about your tax affairs, or work with an accountant on your finances.

If you have not received your UTR after registering, HMRC correspondence typically arrives by post within a few weeks of registration. Our guides to Self Assessment and limited company tax obligations explain how your UTR is used in practice and what you will need it for as your business develops.