VAT & CIS Calculator

How to use the VAT & CIS Calculator

1. Enter the gross or net invoice amount.
2. Select the CIS deduction rate — 20% standard, 30% unverified, or 0% gross payment status.
3. Toggle VAT on or off depending on your VAT registration status.
4. If VAT-registered, confirm that materials are listed separately from labour on the invoice.
5. Review the breakdown showing VAT amount, CIS deduction, and net payment due.
6. Use the summary to check your next payment or to verify the deduction shown on a payment statement.

Why use this tool

• Avoids common invoicing errors that delay subcontractor payments.
• Calculates the correct deduction before the contractor processes payment, reducing disputes.
• Helps subcontractors verify that the right amount has been withheld from their pay.
• Clearly separates the VAT and CIS calculations so you can see exactly how each figure is derived.

The Construction Industry Scheme requires contractors to deduct tax at source from subcontractor payments and pass it to HMRC. Getting the CIS calculation wrong is one of the most common causes of payment disputes on site. VAT-registered subcontractors need to understand that CIS is deducted from the labour element only — materials supplied are typically excluded. If materials and labour are not separated on the invoice, the deduction may be applied to the full amount. This calculator handles the arithmetic so you can focus on getting the invoice right first time. Subcontractors can reclaim CIS deductions through their self-assessment tax return or, if operating through a limited company, through their monthly employer payment summary.

Part of Builder Tools Utilities — free construction tools for UK tradespeople.