What is a UTR number?

By Ben Davies · Updated 26 September 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. Virtually every company has one — HMRC issues a Corporation Tax UTR automatically, usually within about 14 days of incorporation. Having a UTR does not mean HMRC expects a return every year; that depends on whether HMRC has issued a notice to deliver a return (its letter asking for a Company Tax Return, form CT603).

Where to find it

HMRC sends the UTR by post to your company's registered office address shortly after incorporation, on a letter called the CT41G. You can also find it on:

• Other Corporation Tax letters 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?

It is rare for a company not to have a UTR, since HMRC issues one automatically shortly after incorporation. If the letter never arrived or you cannot find it, request a reissue from HMRC using the helpline above. Whether you actually need to file a CT600 is a separate question — it depends on whether HMRC has asked for one, not on having a UTR. If HMRC has not asked, you may 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