CIS refund calculator
Put in your pay from CIS work, the CIS taken off and your costs to see a rough figure for the 2026/27 tax year. It uses the Income Tax and National Insurance rates published on GOV.UK.
ACCA qualified accountants with over 20 years in practice
Estimated refund
£0
| Profit | £0 |
|---|---|
| Personal Allowance | £0 |
| Income Tax | £0 |
| Class 4 National Insurance | £0 |
| Tax and National Insurance due | £0 |
| CIS already paid | £0 |
| Estimated refund | £0 |
This is an estimate from the numbers you enter, not advice. The real figure depends on your full tax return: it does not include student loan repayments, payments on account, tax owed from earlier years or income from a job.
Get the real figure: free quoteIllustrative estimate only. It uses the 2026/27 rates and allowances published on GOV.UK (opens in a new tab) (checked 15/10/2026) and only the figures you enter. It is not tax advice and does not cover your full situation, so we accept no liability for decisions made from it (see our terms). For a figure you can rely on, get a free quote or book a call.
How the estimate works
Your profit is your pay from CIS work plus any other self employed income, minus your costs. Income Tax is worked out on that profit after your Personal Allowance of £12,570, and Class 4 National Insurance on profit between £12,570 and £50,270 at 6%, and above that at 2%.
The CIS taken off during the year counts towards that bill. If it comes to more than the bill, the difference is your estimated refund. If it comes to less, the difference is what you would still owe.
The rates in this calculator come from GOV.UK. Last checked .
Questions about the calculator
How accurate is the calculator?
It is an estimate from the numbers you put in. It leaves out student loan repayments, payments on account, tax owed from earlier years and income from a job, so your real figure comes from your full tax return.
What costs can I include?
Costs you have only because of your work: tools, workwear and protective gear, the work part of your phone bill, insurance and van costs. For a car or van you can use the mileage rate instead, which for 2026/27 is 55p a mile for the first 10,000 business miles.
Why is there a Scotland option?
Scottish taxpayers pay Income Tax in six bands, from 19% to 48%, so the same profit gives a different bill. Class 4 National Insurance is the same across the UK.
What if I leave the CIS box empty?
The calculator assumes 20% of your CIS pay was taken, the rate for registered subcontractors. Your monthly CIS statements show the real total, so use that if you have it.