What is a UTR number?
By DormantFile · Updated 28 March 2026
A UTR (Unique Taxpayer Reference) is a 10-digit number issued by HMRC to identify your company for Corporation Tax purposes. It looks something like 1234567890.
Why it matters
You need your UTR to file a CT600 Corporation Tax return. Without it, HMRC cannot match your filing to your company. It is also the key indicator of whether your company is registered for Corporation Tax — if you have a UTR, you are registered.
Where to find it
HMRC sends the UTR by post to your company's registered office address when the company first registers for Corporation Tax. It appears on:
- The original "Notice to deliver a Company Tax Return" letter from HMRC
- Any Corporation Tax correspondence from HMRC
- Your HMRC online account (if you have set one up)
If you have lost it, call HMRC's Corporation Tax helpline on 0300 200 3410 to request a reissue.
What if you don't have one?
If your company was incorporated but never registered for Corporation Tax, you will not have a UTR. In that case, you do not need to file a CT600 — you only need to file dormant accounts with Companies House. See our guide on whether you need a CT600.
We handle both filings — accounts to Companies House and CT600 to HMRC — from £19/year.
Read the full guide: How to file a nil CT600 tax return with HMRC