Verifying a CIS subcontractor

CIS verification should use the subcontractor’s correct legal details and the official HMRC process where required. Retain the verification outcome and apply the instructed treatment rather than accepting an invoice statement as proof of the deduction rate.

Check whether the payee is an individual, partnership or company and resolve mismatches before payment. A trading name may differ from the name needed for verification.

Match the subcontractor to the contract

Establish whether the payee is a sole trader, partnership or limited company, and identify the legal entity engaged to perform the work. Compare the contract, invoice and supplier record before verification. A familiar trading name can continue after incorporation, while the relevant tax details change. Paying the same person at the same site does not prove that the underlying contracting business is unchanged.

HMRC's verification process uses details appropriate to the subcontractor's legal form and provides the deduction treatment to apply. It also specifies when a previously used subcontractor must be verified again after an absence from returns. Follow the current process and retain the outcome. A statement on an invoice claiming registration or gross-payment status is not a substitute for the contractor's required verification. ^[1]

Gather accurate identifiers securely

Request the required tax and registration details through a controlled onboarding process. Ask the subcontractor to confirm that the information matches the details used with HMRC. Check spelling and number transcription carefully before submitting. A failed match may reflect an input error or a legal-entity mismatch, so investigate the precise discrepancy rather than repeatedly trying variations until one appears to work.

Keep personal tax identifiers out of general site documents and widely shared payment schedules. The person approving completed construction work may need the supplier name and invoice value without needing the UTR or National Insurance number. Use an internal supplier identifier to connect the operational and tax records. This preserves traceability while limiting access to information that is only required by the verification and finance team.

Record the outcome as an instruction with a date

Save the verification result, relevant reference and the date it was obtained against the correct supplier record. Make the instructed deduction treatment visible to the person preparing payments. Avoid storing the result only in an individual employee's inbox, where it may not be found when the next invoice is processed. The contractor should be able to demonstrate which outcome was used for a particular payment.

Review HMRC notifications and changes affecting the subcontractor's treatment. Do not assume the first result remains correct indefinitely despite a subsequent notice or change of entity. Keep the previous outcome and the effective change identifiable so historic statements remain explainable. Overwriting one undated percentage in the supplier master can make it impossible to establish why an earlier deduction differed from the current setting.

Keep verification separate from other assessments

Employment status needs its own review based on the actual working arrangement. Verification does not determine whether a person should be treated as an employee, and CIS should not be used to bypass payroll where employment treatment is required. Ask the person managing the engagement to supply the facts about control, personal service and the way the work is carried out, rather than relying only on the subcontractor's preferred label.

VAT treatment is also separate. A CIS deduction result does not establish whether an invoice should charge VAT, apply a construction reverse charge or have another treatment. Keep the tax decisions distinct in the supplier process and route unfamiliar VAT questions to the appropriate reviewer. Combining all three assessments into a single 'approved subcontractor' tick box hides which checks have actually been completed.

Resolve mismatches before the payment run

Maintain an exception list showing the supplier, missing or inconsistent detail, person contacted and action required. Give subcontractors a clear explanation of the information needed without promising a preferred deduction rate. Where the deadline is close, seek the appropriate advice about the payment and deduction obligations rather than choosing the rate claimed verbally by the subcontractor or delaying the tax decision until after the transfer.

Read Employment status in construction work for employment-status questions and CIS return support to discuss CIS verification administration. Initially describe the legal form and nature of the mismatch without sending a complete list of subcontractors' tax identifiers. Use the agreed secure route for the specific records needed to establish the correct entity and verification outcome.

After the first payment, compare the deduction used with the saved verification result and the statement issued. Investigate any difference caused by a stale supplier setting or an imported rate. Correct the underlying record as well as the affected payment, and preserve the evidence showing when the change was approved and applied.

Illustrative scenario

A contractor receives an invoice under a new trading name. The accounts team confirms the underlying legal entity and completes the required verification instead of reusing another supplier’s details.

Preparation checklist

• Confirm the legal payee
• Check identifying details
• Retain verification evidence
• Apply the verified treatment