How Do I Claim My CIS Refund? A Step-by-Step Guide for Subcontractors

The Short Answer

You claim a CIS refund in five steps. Check you are actually due one. Gather every CIS payment and deduction statement for the tax year. Add up your income and your allowable expenses. File your tax return for that year, including the total CIS deducted. Then make sure HMRC has your bank details so the refund can be paid.

The return does the claiming. HMRC compares the tax you owe for the year with the tax already taken by your contractors, and if more was taken than you owe, the difference comes back to you. Nobody applies for a CIS refund separately, and nobody needs to pay a refund company to do it.

This guide is for self-employed subcontractors: sole traders paid under CIS. If you work through your own limited company, deductions are reclaimed through the company's payroll submissions instead, and the steps below do not apply.

Step 1: Check You Are Due a Refund

You can only get back tax that was taken. If a contractor has been deducting 20% (registered subcontractor) or 30% (not registered), you have paid tax in advance and may be owed some of it. If you hold gross payment status, nothing is deducted, so there is nothing to refund.

The deduction is often more than you owe, for two reasons. It applies only to the labour part of your invoice, not materials or VAT, and it is a flat rate: it takes no account of your Personal Allowance (£12,570 for 2025–26, the income most people pay no tax on) or your expenses. HMRC sets your CIS deductions against your actual Income Tax and Class 4 National Insurance, worked out on your profit, and refunds any overpayment. Our guide on why CIS subcontractors often overpay goes into this in more detail.

You might not get a refund, or might get less than you expect, if you have other income that uses up your Personal Allowance, such as a PAYE job, a pension or rental income, or if you repay a student loan through Self Assessment. Those are added into the same calculation.

Step 2: Gather Every CIS Statement

Your contractor must give you a payment and deduction statement for every tax month in which they paid you, within 14 days of the end of that tax month. Tax months run from the 6th of one month to the 5th of the next. Each statement shows the gross amount paid, the cost of materials, and the amount deducted.

Add up the amount deducted across every statement from every contractor for the tax year (6 April to 5 April). That total is the tax you have already paid, and it is the figure your refund depends on.

If a statement is missing, ask the contractor for a copy. They report every deduction to HMRC each month, so HMRC already holds a record of what was taken, but you still need your own figures to check it against. A statement you never chase is a deduction you may never get back.

Step 3: Work Out Your Income and Expenses

Your income is the full amount you invoiced, before any CIS deduction, including any materials you charged for. Recording what landed in your bank instead understates your income, and the numbers will not match what your contractors reported.

Your allowable expenses are the costs of doing the work: materials you bought, tools and equipment, van running costs or mileage at the approved rates, fuel, public liability insurance, protective clothing, trade subscriptions and the business share of your phone. Every expense you leave out adds to your profit and takes away from your refund.

A worked example, using the 2025–26 rates for England, Wales and Northern Ireland. Over the year you invoice £34,000, of which £4,000 is materials. Your contractor deducts 20% of the £30,000 labour, so £6,000 is taken. Your expenses are the £4,000 of materials plus £5,000 of van, fuel, tools and insurance, leaving a profit of £25,000.

Income Tax is 20% of the £12,430 above your Personal Allowance, which is £2,486. Class 4 National Insurance is 6% of the same £12,430, which is £745.80. Your total bill is £3,231.80. HMRC already holds £6,000, so the refund is £2,768.20. Scottish taxpayers pay slightly different Income Tax rates, so their figure will differ a little.

Step 4: File the Right Return for the Year

This is where the tax year matters, because Making Tax Digital for Income Tax changed how returns are filed from 6 April 2026.

For 2025–26 (6 April 2025 to 5 April 2026) and earlier years, you claim on an ordinary Self Assessment return. You can file it now: there is no need to wait for the 31 January 2027 deadline, and filing early gets the money back sooner. HMRC's own online Self Assessment service is free and handles CIS; you enter your income, expenses and the total CIS deducted on the self-employment pages. FileThat does not file these years.

For 2026–27 onwards, it depends on whether you are in Making Tax Digital. If your income puts you in MTD (see what MTD means for builders and subcontractors), or you have joined voluntarily, you send quarterly updates through the year and then a final declaration after 5 April 2027, and your refund comes from that final declaration. If you are not in MTD, you file an ordinary Self Assessment return for the year, as before.

Either way you cannot claim part-way through the year. A self-employed subcontractor's refund comes once the tax year has ended and the return or final declaration for it has been filed.

Step 5: Get the Money Paid to You

Include your bank details when you file, or add them in your HMRC online account. When HMRC has processed the return it pays the overpayment back to you, usually within a few weeks. 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.

HMRC can set the overpayment against anything else you owe it first, such as tax outstanding from another year, and pay you the rest. Your HMRC online account shows the calculation and whether a repayment has been issued.

Claiming CIS Tax Back for Earlier Years

You have four years from the end of a tax year to claim. Tax year 2022–23 ended on 5 April 2023, so its deadline is 5 April 2027. Anything older than that is out of time and stays with HMRC.

If you never filed a return for an earlier year, filing it now claims the refund, although a late return can carry a late filing penalty. If you filed but left out some CIS deductions or expenses, you can amend that return within 12 months of the filing deadline, or make an overpayment relief claim to HMRC after that, still within the four years.

Watch Out for Refund Scams and Refund Companies

HMRC does not tell you about a refund by text or email and ask you to click a link or enter bank details. Messages like that are scams, however genuine they look. Check your refund in your HMRC online account instead, by going to it directly rather than through a link.

Some companies offer to claim your CIS refund in return for a percentage of it. The refund is the same whoever files, so read the fee before you sign anything, and be especially careful with any agreement that has HMRC pay your refund to them rather than to you.

Claiming Your CIS Refund With FileThat

FileThat is Making Tax Digital software for tax years from 2026–27. The income and expenses ledger is free to use all year, so your figures are ready when the year ends. The CIS Deductions screen shows the deductions your contractors have reported to HMRC, and lets you add any that are missing so the total matches your statements.

After 5 April 2027 you submit your final declaration from the same place, and HMRC calculates your refund. Filing your CIS deductions and your final declaration costs nothing in FileThat. You pay only for the quarterly updates, and there is no monthly subscription. See how FileThat works for the trades.