What is a UTR number and where do I find it?

A UTR, or Unique Taxpayer Reference, is the 10-digit number HMRC gives you when you register for Self Assessment. It arrives by post about 15 days later. As at 16 October 2026, the HMRC app shows it too.

For a subcontractor, the UTR does a lot of work. You need it to register for the Construction Industry Scheme (CIS) online. Contractors need it to verify you with HMRC before they pay you. It appears on every monthly payment and deduction statement, and it is the reference for your tax return, where you claim your CIS deductions back.

Where to find your UTR

If you cannot find it anywhere, GOV.UK says to contact HMRC. A limited company has its own Corporation Tax UTR, which you can request online and HMRC sends to the company's registered address.

Why it matters for CIS

When you start with a new contractor, GOV.UK says to give them the exact details you used when you registered for CIS, including your UTR and your legal business or trading name. For a sole trader, the contractor also needs your National Insurance number. GOV.UK says temporary numbers, starting with "TN" or 2 digits, cannot be used to verify.

HMRC then tells the contractor which rate to use: 20% if you are registered and verified, nothing if you have gross payment status, and 30% if you cannot be matched. A single wrong digit in your UTR, or a different spelling of your name, can mean the higher rate. The extra 10% is not lost, because it counts towards your tax bill, but you wait until after the tax year to get it back.

What this means for you

If you are new to self-employment, getting your UTR is the first job, because CIS registration online depends on it. GOV.UK offers a shortcut: register as a new business for Self Assessment and choose "working as a subcontractor" when asked, and you are registered for Self Assessment and CIS at the same time.

If you were registered for Self Assessment before, for example in an earlier spell of self-employment, GOV.UK says you may need to reactivate your Self Assessment account, and that a return can be delayed if you file without doing so.

Treat your UTR like your bank details. Give it to contractors and to anyone acting for you, but be wary of unexpected calls, texts or emails asking for it.

Steps to get or find your UTR

1. Check the HMRC app or your personal tax account. If you have registered before, it will be there.
2. If not, look on old tax returns and HMRC letters for a 10-digit tax reference.
3. If you have never registered, register as a new business for Self Assessment and choose "working as a subcontractor".
4. Wait about 15 days for the letter with your UTR. You can check HMRC's expected reply times online.
5. Give each contractor your UTR, National Insurance number and the exact name you registered with.
6. Check your first payment and deduction statement shows the right UTR and a 20% rate.
7. Keep the UTR with your records. You will need it for every tax return.

Deadlines that depend on it

If you started working for yourself in the 2025-26 tax year, GOV.UK says you had to tell HMRC by 5 October 2026 by registering for Self Assessment. If you have missed that date, register now. You could get a penalty. Your online 2025-26 return is due by 31 January 2027, or 3 months from the date of HMRC's notice to file if it is dated after 31 October 2026. The tax is still due by 31 January 2027.

Use the free MTD check to see whether Making Tax Digital applies to you from April 2027, and visit the trades section for more on CIS.