CIS Refund Calculator
CIS takes a flat 20% or 30% off your labour with no regard for your Personal Allowance or your expenses. Your real tax bill accounts for both, which is why most subcontractors are owed money back. Work out roughly how much.
Rebate or refund, same thing #
This CIS tax rebate calculator and a CIS tax refund calculator are the same tool under two names. HMRC calls the money a repayment, the trade usually calls it a rebate, and most people search for a refund. Whichever word you use, it is the gap between what CIS took from your labour and what you actually owed once your Personal Allowance and expenses were counted.
Why CIS overcollects #
CIS is a blunt instrument. It takes 20% of your labour whatever your circumstances. It does not know that your first £12,570.00 of income is tax free, and it does not know what you spent on materials, tools, your van or your insurance.
Your actual bill accounts for both. So the flat deduction usually collects more than you owe, and the difference comes back after you file.
What counts as an expense #
Understating this is the most common way subcontractors leave money with HMRC. Commonly allowable:
- Materials you paid for and were not reimbursed separately
- Tools, and replacement of tools
- Van running costs, or mileage if you use the flat rate instead
- Protective clothing and safety equipment
- Public liability and tool insurance
- Phone, where used for work
- Accountancy and bookkeeping fees
- CITB levy and trade subscriptions
What this calculator does not cover #
Deliberately kept simple. It does not handle:
- Scottish taxpayers. Scotland sets different Income Tax bands. National Insurance is the same UK-wide.
- Student loan repayments
- Pension contributions and Gift Aid, both of which extend your basic rate band
- Payments on account already made towards this year
- Capital allowances on larger purchases
- Marriage Allowance and other transferable allowances
Treat the figure as an estimate for planning. The exact number comes out of your Self Assessment return.
A CIS tax return calculator, not just a refund estimate #
This doubles as a CIS tax return calculator, because it runs the same calculation your Self Assessment return will: income, less expenses, less the Personal Allowance, then Income Tax and Class 4 National Insurance, with the CIS already deducted set against the total.
The refund is whatever is left over. Nothing arrives automatically, so the figure here is an estimate of what filing will release rather than of something HMRC is about to send you. The process is in claiming your CIS refund, and every date is in Self Assessment deadlines.
CIS tax return accountants commonly charge a percentage of the refund, often 20% to 30%. On a £3,000 refund that is £600 to £900 for a return many subcontractors can file themselves. Worth knowing the figure before agreeing to a percentage of it.
Common questions #
Why do CIS subcontractors get a refund?
Because CIS deducts a flat 20% or 30% from labour with no regard for your Personal Allowance or your expenses. Your actual tax bill takes both into account, so the flat deduction usually collects more than you owe.
How long does a CIS refund take?
HMRC generally pays within a few weeks of processing the Self Assessment return, though it can take longer if the return is selected for checks or if bank details are missing.
Do I still need to file a tax return?
Yes. The refund is not automatic. It is worked out through Self Assessment, and the deadline for an online return is 31 January after the end of the tax year.
What if the calculator shows I owe money?
That happens when profits are high enough that the tax and National Insurance due exceed what was deducted, or when a lot of income came from work outside CIS. The balance is payable by 31 January.
Working out a single invoice instead? Use the CIS deduction calculator.