cissplitTry it free

Is my CIS deduction right?

Free. Enter the figures from one invoice or payment and we'll work out the amount liable to deduction the way GOV.UK describes, then show 20% and 30% of it and whether the deduction taken matches.

The total on your invoice or the contractor's statement, before any CIS deduction.

Are you registered for VAT?

What you actually paid for materials, consumable stores, fuel (except fuel for travelling), plant hire, and manufacturing or prefabricating materials. Include any VAT you paid on them. Leave blank or enter 0 if none.

The deduction on the statement or payment. Enter 0 if nothing was taken.

Your CIS registration

This isn't tax, accounting or legal advice. Nothing you type leaves your device.

Your result

Fill in the figures and choose Check the deduction. Your result appears here.

GOV.UK says

Work out the gross amount from which a deduction will be made by excluding VAT charged by the subcontractor if the subcontractor is registered for VAT …

Deduct from the gross payment the amount the subcontractor actually paid for the following items used in the construction operations, including VAT paid if the subcontractor is not registered for VAT:

  • materials (read paragraph 3.13)
  • consumable stores
  • fuel (except fuel for travelling)
  • plant hire (read paragraph 3.14)
  • the cost of manufacture or prefabrication of materials

Source: GOV.UK, CIS 340, paragraph 3.12 (checked 19 October 2026)

Got a year of statements? Add up 3 CIS statements free with cissplit: it checks every deduction and gives you the tax-year totals.

This checks one deduction against GOV.UK's published rule, using the figures you type. It doesn't work out your tax, a refund or what you're owed, and it isn't connected to HMRC. If a figure looks wrong, check the statement and speak to the contractor.