Use this calculator to organise an arithmetic illustration of a CIS deduction after the actual HMRC verification outcome is known. It does not verify a subcontractor, decide eligibility of materials or establish tax status.
What to enter
Enter the invoice amount, VAT where shown, and established exclusions supported by the payment record. Choose only the verified HMRC outcome: 0% gross payment, 20% or 30%. Do not use the calculator to guess a rate.
What the result means
The deduction base is the invoice less VAT and established exclusions. The result shows the deduction and net payment using a consistent penny basis. A zero deduction base can be an arithmetic result; it does not prove that an exclusion is allowable.
Worked example
An invoice of £720 less £120 VAT and £200 established exclusions leaves a £400 deduction base. At a verified 20% outcome, the deduction is £80 and the net payment is £640.
Limitation and next step
Keep HMRC’s verification response and the supporting evidence with the payment record. Check the current CIS guidance where the supply, materials or status is unclear.
Important
General information only. It is not a tax, accounting, legal or financial determination for a particular business.
Next step
Retain the payment, materials and verification evidence, then use the confirmed HMRC result rather than this guide to complete the payment record.
Sources and review
- Evidence check date: 5 November 2026.
- GOV.UK - Make deductions and pay subcontractors