How to verify a CIS subcontractor

Verify a subbie before you pay them for the first time. You can't verify until you have a contract with them or have formally accepted their tender.

You don't need to verify a subbie you've included on one of your CIS returns in the current tax year or the two before it. In the 2026 to 2027 tax year, that means anyone on one of your returns since 6 April 2024.

Once you've verified a subbie, you can keep paying them at the rate HMRC gave you. HMRC writes to you if that rate changes, as long as you've verified them or had them on one of your returns in the current tax year or the two before it. If you haven't verified them or had them on one of your returns since 6 April 2024, verify them again.

If you don't need to verify, pay them the same way as last time.

Verifying tells you what rate to deduct. HMRC also looks at what other checks you made before you paid. Since 6 April 2026, HMRC can charge you 20% of a payment if you should have known the subbie, or someone else on the job, was deliberately dodging CIS or PAYE. Keep a note of what you checked and when. See CIS penalties.

Your own details first: your name, your Unique Taxpayer Reference (UTR), your accounts office reference and your employer reference. Then the subbie's, which depend on how they're set up:

• Sole trader: their name, UTR and National Insurance number.
• Partnership: the partnership's name and UTR, plus the nominated partner's name and their UTR or National Insurance number. If the nominated partner is a company, its UTR or company registration number.
• Limited company: the company name, its UTR and its company registration number.

The details must match what the subbie gave HMRC when they registered. A temporary National Insurance number, one starting with TN or with two digits, can't be verified.

HMRC's answer tells you which of three ways to pay the subbie:

The rate is taken off the payment less VAT and the subbie's cost of materials, not off the whole invoice. The CIS deduction calculator works it out for one payment.

If HMRC can't match the details you give to a CIS registration, the subbie comes back unmatched and you take 30% from every payment. That happens when they aren't registered for CIS, and it can happen when a name or number doesn't match HMRC's record, so check the spelling and the trading name before you send.

If they aren't registered, the subbie contacts HMRC to register for CIS. HMRC then writes to you with the rate to use from then on. Until it does, keep taking 30%.

Every verification gets a reference that starts with V and has 10 digits, such as V0004528765. Subbies you verify together share one number. An unmatched subbie gets the same number with one or two letters on the end, such as V0004528765A, so each one is unique.

Keep it. For a subbie you pay at 30%, the number goes on your monthly CIS return and on every statement you give them, because they need it to claim the deductions back from HMRC. For subbies paid gross or at 20% it doesn't have to go on either.

A subbie you haven't included on any of your CIS returns in the current tax year or the two before it has to be verified again before you pay them.

Otherwise, keep paying each subbie at the rate you have until HMRC tells you it has changed. HMRC writes to you if a subbie gains or loses gross payment status or stops being registered, as long as you've verified them, or put them on a CIS return, this tax year or in the last two. It usually gives you 35 days' notice before a gross subbie moves to deductions, but if HMRC cancels gross payment status for fraud, the change takes effect straight away.