How much CIS refund will you get?
Enter your CIS payments, the deductions taken and your expenses, and see an estimate of your refund or what is left to pay. It works for 2025-26 and for 2026-27, the first year of Making Tax Digital for Income Tax.
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Based on the gov.uk rates
Why CIS subcontractors are often owed money
Under the Construction Industry Scheme, a contractor takes 20% off the labour part of your pay, or 30% if you are not registered, and passes it to HMRC. That is tax paid in advance, at a flat rate.
The flat rate takes no account of your expenses or your Personal Allowance, the first £12,570 most people pay no tax on. Your real bill is Income Tax and Class 4 National Insurance on your profit for the year. If the deductions come to more than that, HMRC pays the difference back.
Class 2 National Insurance is not part of the sum. Since 6 April 2024 the self-employed no longer have to pay it, although someone with low profits can still choose to pay it to protect their State Pension record.
How to claim it
Wait for the year to end
A tax year runs from 6 April to 5 April. Your refund depends on the whole year's profit, so you claim after 5 April, not during the year.
Gather your statements
Add up the deductions on every monthly CIS statement from every contractor. That total is the tax already paid.
File your return
Put your income, expenses and CIS deducted on your Self Assessment return, or your final declaration if you are in Making Tax Digital.
Get paid
HMRC works out the real bill and pays back the overpayment to your bank account, usually within a few weeks.
What this estimate leaves out
Scottish Income Tax
It uses the rates for England, Wales and Northern Ireland. Scottish taxpayers pay different Income Tax rates, so their figure will differ. Class 4 is the same across the UK.
Student loans
Student loan or postgraduate loan repayments collected through Self Assessment are added to your bill and can take a large part of a refund.
Payments on account
If you still owe more than £1,000 once deductions are taken off, HMRC may also ask for advance payments towards next year. Those are not included.
Other income and reliefs
Pension contributions, Marriage Allowance, losses from earlier years, rent, savings and dividends all change the answer. The only other income it includes is pay from a job.
This is an estimate. HMRC works out the real figure from your return. For the claim itself, read how to claim your CIS refund, step by step.
Straight answers
How does a CIS refund work?
Your contractor takes 20% or 30% off the labour part of your pay and sends it to HMRC as tax paid in advance. After the year ends, HMRC works out the Income Tax and Class 4 National Insurance you really owe on your profit. If the deductions were more than that, it pays you the difference.
When can I claim my CIS refund?
Once the tax year has ended on 5 April. You claim through your Self Assessment return for that year, or your final declaration if you are in Making Tax Digital. For 2025-26 you can file now, without waiting for the 31 January 2027 deadline, and filing early gets the money back sooner.
How long does a CIS refund take?
Usually a few weeks after HMRC has processed your return, as long as it has your bank details. It can take longer if HMRC runs security checks or needs to confirm your figures, which is more likely on a first return or a large refund.
What expenses can a builder claim?
The costs of doing the work: materials you paid for, tools and equipment, van running costs or mileage, fuel, public liability insurance, protective clothing, trade subscriptions and the business share of your phone. Everyday clothes, travel to a permanent workplace, fines and the CIS deductions themselves do not count.
Why is my refund smaller than I expected?
Usually because something else shares the same calculation. A job or a pension can use up your Personal Allowance, student loan repayments are added to the bill, and HMRC can set a refund against tax you owe from another year. Missing expenses also raise your profit and shrink the refund.
Does this calculator work if I live in Scotland?
Only roughly. Scottish taxpayers pay Scottish Income Tax, which has different rates and bands, so the Income Tax part of this estimate will not match. Class 4 National Insurance is the same across the UK, and so is the way CIS deductions are refunded.
Keep your CIS figures ready for the refund
4 free credits, no card needed. Record your income and expenses as you go, and send your final declaration with HMRC-recognised software. The final declaration is free to file.
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