How do I claim a CIS refund as a builder?

You claim it back after the tax year ends on 5 April. For 2026-27, sole trader builders can file their return from 6 April 2027. Under Making Tax Digital, the refund is requested separately through HMRC online services.

Under the Construction Industry Scheme (CIS), what a contractor takes off your pay is an advance payment towards your Income Tax and National Insurance. It is usually 20% of the labour part of your invoice if you are registered, or 30% if you are not. Your real bill depends on your profit after costs such as your van, tools and materials, so many builders pay more through CIS than they owe. Over-deducted CIS is claimed back through your tax return. The sooner after 5 April you file, the sooner HMRC can repay you. This page is for sole traders and follows GOV.UK as checked on 18 October 2026. A limited company uses its deductions through its payroll instead, as our guide on whether a limited company can claim back CIS deductions explains.

Which route applies to you

Making Tax Digital for Income Tax (MTD) started on 6 April 2026 for sole traders whose 2024-25 return showed self-employed and rental income over £50,000 before costs. It starts on 6 April 2027 if the 2025-26 return shows over £30,000. For CIS work, in our reading the gross pay before deductions is what counts, because that is the turnover on your return.

A worked example for a builder

Dan is a self-employed bricklayer outside Scotland with no other income. In 2026-27 his contractors pay him £45,000 for labour, before deductions, and take 20%. He supplies no materials. His van, tools, fuel, phone and insurance come to £9,000.

These are 2026-27 rates. Class 2 National Insurance is treated as paid because Dan's profit is above £7,105, so it adds nothing. His 2025-26 return showed more than £30,000, so he joins MTD on 6 April 2027. His 2026-27 return is still an ordinary Self Assessment return, so he claims this refund in it. From 2027-28 he requests refunds through his HMRC online services account. This is an example only, and your figures will differ.

Steps to claim your CIS refund

1. Collect every payment and deduction statement for the tax year, 6 April to 5 April. A contractor who takes a deduction must give you one within 14 days of the end of that tax month, so the last one for 2026-27 is due by 19 April 2027.
2. Ask each contractor for any statement that is missing. If a contractor has gone out of business, write to HMRC with your details, the contractor's details, the dates you were paid and why you have no statements.
3. Add up your pay before deductions and the total deducted, and check each statement against your bank account.
4. Total your business costs, such as materials you paid for, tools, van costs and phone bills, and keep the receipts.
5. Add any work you did directly for homeowners. It has no CIS deduction, but it goes on the same return.
6. If you are not in MTD for the year, complete your Self Assessment return with your gross pay as turnover and the total deductions in the CIS box, give your bank details and file online.
7. If you are in MTD, check the CIS deductions HMRC has added to your MTD tax return, correct them in your software if they are wrong, submit the return, then request the refund through your HMRC online services account.

What this means for you

Your deductions are not lost money. They sit with HMRC against your name until your return is in. The deadline for a 2026-27 return is 31 January 2028, but filing in April 2027 instead puts your claim in up to ten months sooner.

Builders who buy their own materials should watch their statements closely. CIS 340 says the deduction is only taken from the part of a payment that is not the direct cost of materials. If a contractor takes 20% off materials too, you get it back at the year end, but you wait months for money you should never have lost. Show materials separately on every invoice and keep the merchant receipts.

Be wary of anyone who promises a refund by a set date. Only HMRC decides when it pays.

If something looks wrong

• You were charged 30%. If you are registered but the contractor could not verify you, it takes 30%. GOV.UK says to speak to your contractor if you think the figures are wrong. The extra still counts towards your tax on the return.
• HMRC's figures differ from your statements. Check with the contractor first. Our guide on checking your CIS deductions with HMRC sets out each route.

Use the free MTD check to see when MTD starts for you, and visit the trades section for more on CIS and tax for builders.