CIS Tax Calculator
Calculate your CIS deductions, annual tax summary, and potential refund for 2025/26. See how much CIS is deducted per payment, your full-year tax position, and whether you can reclaim overpaid tax through self-assessment.
Try another scenario
How to Use This Calculator
CIS Deduction tab
Enter the gross payment amount, your CIS registration status (20% registered, 30% unregistered, or 0% gross payment status), and the materials cost included in the payment. The calculator works out the labour portion (gross minus materials), applies the correct CIS deduction rate, and shows the net payment you receive plus the effective rate after materials. Expand "More options" to add VAT details if you are VAT-registered.
Annual Summary tab
Enter your total gross income for the year, total CIS deducted, total materials, and allowable expenses. The calculator computes your gross profit, taxable profit, income tax, Class 2 NI, and Class 4 NI, then offsets your CIS deductions to show whether you are owed a refund or have a balance to pay. Use "More options" to add VAT details or other income sources.
Reclaim Check tab
Enter your total CIS deducted and your actual tax + NI liability (you can calculate this using the Annual Summary tab). The calculator shows your potential refund amount, how to claim it through self-assessment, and the deadline date.
Share your result
Every input is encoded in the URL. Click Share to send your exact scenario to an accountant, business partner, or save it for later.
The Formula
CIS deductions are calculated on the labour element of each payment only:
CIS Deduction = Labour × CIS Rate
CIS Rates:
• 20% — registered subcontractor
• 30% — unregistered subcontractor
• 0% — gross payment status
Net Payment = Gross Payment − CIS Deduction
Annual Tax Position:
• Gross Profit = Gross Income − Materials
• Taxable Profit = Gross Profit − Allowable Expenses
• Total Liability = Income Tax + Class 2 NI + Class 4 NI
• Balance Due = Total Liability − CIS Deductions Paid
• If negative = Refund due to you via Self Assessment
CIS deductions are not an extra tax. They are advance payments of your income tax and NI. If your CIS deductions exceed your actual tax liability, you receive the difference as a refund through your Self Assessment return.
Materials must be the actual cost of materials used for the job. The contractor verifies the materials figure before excluding it from the CIS deduction calculation. Labour-only subcontractors have no materials deduction.
Example
Dave — Self-employed Bricklayer, Manchester
Dave is a CIS-registered subcontractor. He receives a gross payment of £5,000 for a job, of which £1,500 is materials. His annual gross income is £60,000 with £15,000 materials and £5,000 expenses.
Single Payment (CIS Deduction)
Annual Summary
Reclaim Check
Dave has overpaid by £689. He reclaims this through his Self Assessment return filed by 31 January 2027. This is common for CIS subcontractors whose deductions exceed their actual tax liability.