What does unmatched mean when a contractor verifies me under CIS?

Unmatched means HMRC could not link the details your contractor gave to a CIS registration. In 2026-27 that means 30% is taken, not 20% or nothing, until you are registered and your name, UTR and National Insurance number match.

Before a contractor pays a new subcontractor under the Construction Industry Scheme (CIS), it verifies them online with HMRC. For a sole trader it sends three things: your Unique Taxpayer Reference (UTR), your National Insurance number, and the name or trading name HMRC knows you by. GOV.UK says these must exactly match the details you used to register. HMRC's system then looks for your CIS record and gives one of three answers.

The three possible answers

CIS 340 explains the numbering. Everyone verified at the same time shares one reference. Anyone HMRC cannot verify gets that reference with one or two letters added, so it belongs to them alone. The contractor must put it on the monthly return and on your payment and deduction statement whenever 30% is taken.

Why the match fails

HMRC's manual gives two main reasons: you have not registered, or finished registering, for CIS; or the contractor's details were incomplete or misquoted. In practice that can be a wrong digit in a UTR, a name that differs from the one you registered with, or a temporary National Insurance number, which GOV.UK says cannot be verified.

Where the UTR is recognised but the name and National Insurance number do not agree with HMRC's records, the manual says the system marks the unmatched verification as "suspect". That is an internal flag for a closer look. The fix is the same: get the details right.

An unmatched result can also outlast its cause. A contractor who has included you on a return in the current or previous 2 tax years does not have to verify you again, and keeps paying on the same basis until HMRC says otherwise. HMRC's manual says that notice comes once it matches your record: it writes to the contractor confirming the rate for future payments.

What it costs while it lasts

Take £3,000 of labour a month. At 20% the contractor takes £600; at 30% it takes £900. That is £300 a month more held by HMRC, or £900 over a quarter.

The money still counts towards your tax. Before you join Making Tax Digital, over-deducted CIS is claimed back through your Self Assessment tax return. Once you are in Making Tax Digital, HMRC adds your CIS deductions to your tax return, and any refund is requested separately through HMRC online services.

What this means for you

The verification number is the thread that ties the 30% payments to you. HMRC's manual says it uses that number to link payments made under it to your CIS record, so your yearly totals are complete. It also notes that payments taken before you registered do not flow to your record automatically. Keep every statement showing the number.

If you have lost the number, HMRC can trace it from the contractor's employer scheme or accounts office reference and the approximate date of verification. If it cannot link the number to your record, the manual says the case stays unmatched and 30% continues. So act on the first statement that shows a letter on the end.

Steps to fix a mismatch

1. Find the verification number on your statement. One or two letters on the end mean you were unmatched.
2. Check you are registered for CIS. If not, register online or by post. Once you are registered, HMRC's manual says it sends form CIS316B to contractors who took 30%, telling them the new rate.
3. Give the contractor your details exactly as registered: your UTR, your permanent National Insurance number and the name HMRC holds.
4. Ask the contractor to verify you again before the next payment. The manual says a fresh check with corrected details, made before payment, can cancel the unmatched result.
5. Or call the CIS helpline on 0300 200 3210 with your UTR and the unmatched number. HMRC can link the payments to your record and send the contractor form CIS316A confirming the rate for future payments.
6. Claim all deductions taken, including the 30% months, on your tax return for that year.

The free MTD check shows when Making Tax Digital starts for you, and the trades section has more on CIS. The guide to working out a CIS deduction shows how the amount is calculated.