Free tools
Free tax and CIS calculators
Two sums I want written down before the money gets spent. I've spent over 20 years in UK construction, and January and a subcontract invoice are where a rough figure still catches people out. Both of these run in the browser. Neither is tax advice.
2026 to 2027
How much should I put aside for tax?
Income tax, Class 4 National Insurance, and a monthly and weekly amount to set aside for a sole trader. Scotland has its own income tax bands. If contractors have already taken CIS, it shows a refund or what is still owed.
Open the tax calculator
One invoice
CIS deduction calculator
Labour amount, the CIS deduction, and the net payment. 20% if you are registered, 30% if you are not, or 0% on gross payment status. Materials and VAT come off before the percentage.
Open the CIS calculator
The rates were read from GOV.UK on 18 October 2026, and each calculator links the page the figure came from. I have not invented a percentage of turnover to put aside. If a year includes other income, a student loan, or a limited company, use the HMRC page or ask an accountant.
Free checklist and the weekly email
Get the Self Assessment checklist
The printable list for the 2025 to 2026 return, due 31 January 2027, comes with the weekly email. One email a week. Unsubscribe any time. The calculator above is an estimate, not tax advice.
What is on the sheet is on the Self Assessment checklist.