CIS tax calculator 2026/27
Two answers subcontractors need: what the contractor will deduct from this invoice, and whether you'll get a refund at the end of the year.
This invoice
| CIS deduction (on labour only) | |
| VAT charged | |
| Paid to you |
Year-end estimate ()
| Profit | |
| Income tax due | |
| Class 4 NI due | |
| Total due | |
| Already deducted under CIS |
Refunds are claimed through your Self Assessment return after 5 April. Most registered subcontractors overpay because the 20% deduction ignores the personal allowance and expenses.
Estimates only; England/Wales/NI bands; assumes no other income. Not tax advice.
Frequently asked questions
What is the CIS deduction rate?
20% for subcontractors registered with HMRC, 30% if not registered, and 0% if you hold gross payment status. Deductions apply to the labour element only, not materials or VAT.
Why do CIS subcontractors get refunds?
The 20% deduction ignores your personal allowance and expenses, so most sole-trader subcontractors have paid more than they owe by the end of the year. The refund is claimed on your Self Assessment return after 5 April.
Do I still need to pay Class 4 NI under CIS?
Yes. CIS deductions are income tax paid in advance; income tax and Class 4 National Insurance are both worked out on your Self Assessment return and the deductions are set against the total.