About UK CIS Deduction Calculator

UK CIS Deduction Calculator is a free, focused reference tool for subcontractors, sole traders, builders, tradespeople, small construction businesses and contractors who want a quick sense-check of a CIS deduction and the cash amount payable.

What this site does

The calculator handles the three current CIS deduction outcomes — 20%, 30% and gross payment status — and shows how qualifying direct materials and common VAT treatments affect the calculation. It is deliberately not a CIS filing, verification, bookkeeping, payroll or accounting system.

How we keep it useful

Calculation rules and explanatory content are checked against primary HMRC and GOV.UK guidance. The visible “rules checked” date is updated when we review those sources. Our methodology page explains the calculation and links to the official guidance used.

About Klamic

This calculator is a free utility from Klamic.com, a simple UK invoicing service. Klamic is promoted on this site in clearly identifiable house advertising and contextual links.