CIS Tax Refund Guide for Self Employed Subcontractors

A CIS tax refund is money HMRC pays back when contractors have deducted more tax from your payments than you actually owe. Sole traders and partners claim it through a Self Assessment tax return after the tax year ends, recording total pay before deductions as income and contractor deductions separately.

The deduction comes off your invoice, not your profit. Your contractor applies the CIS rate before you’ve knocked off a single tool, a mile of travel or a night away from home, so the sum HMRC ends up holding and the sum you actually owe get worked out on two different figures.

This guide covers sole traders and partners. If you subcontract through a limited company, the money comes back through your payroll scheme instead, and GOV.UK warns that using your Corporation Tax return for it can attract a penalty. Three things change the answer for everyone else: whether you’ve registered for CIS, whether you hold gross payment status, and whether you also had PAYE work during the year.

How a CIS tax refund actually arises

CIS deductions aren’t a separate tax. HMRC treats them as advance payments towards your tax, handed to HMRC by your contractor instead of being paid to you. The Construction Industry Scheme exists to collect tax at source from self-employed people working in construction.

The deduction doesn’t come off the whole invoice, and it doesn’t come off your profit either. GOV.UK’s contractor guidance says to start with the gross invoice, strip out VAT, plant hire, fuel used other than for travelling, consumable stores and any materials you paid for directly, then apply the rate to what’s left.

Your actual bill is worked out on profit, which is what remains once every allowable business cost comes off. Two different bases, and the rate lands on the larger one.

A CIS tax refund arises where the deductions taken across the year come to more than the tax and National Insurance your return finally calculates. Nothing about it is automatic. HMRC works out the difference once the return is in, not before.

CIS deductions come at three different rates

There isn’t a single CIS tax rate. Three rates operate under the scheme:

• 20% for registered subcontractors, which GOV.UK calls the standard rate.
• 30% where you aren’t registered, can’t be verified, or gave a business name that doesn’t match HMRC’s record.
• 0% for subcontractors holding gross payment status, who are paid in full and settle up afterwards.

Contractors deduct 30% where you aren’t registered, which is the consequence GOV.UK sets out rather than a penalty for breaking a rule. Ten percentage points separate a 20% CIS deduction from a 30% CIS deduction, and that gap comes off every payment falling inside the scheme. Choosing to register for CIS moves future payments to the standard rate.

The over-deduction already taken isn’t lost. You claim CIS tax back the same way as any other overpayment, through the return.

Give your contractor the exact legal or trading name you registered under, along with your UTR number, so they can verify you. A mismatch is one of the three things that triggers the higher rate, alongside not being registered and not being verifiable.

Gross payment status sits outside all of this. It changes how you pay tax rather than how you claim it back.

Your Self Assessment return does the claiming

There’s no dedicated form for a subcontractor tax refund on the normal route. The claim is a couple of figures on your ordinary Self Assessment tax return.

HMRC asks sole traders and partners to record two figures: total pay before deductions as income, and the total contractors deducted as CIS deductions. HMRC calculates the tax due, takes the deductions off, and repays the difference where there is one.

“CIS tax return” is only shorthand for that return, incidentally. The monthly CIS return is a contractor’s obligation, not a subcontractor’s.

Mixing CIS and PAYE in one tax year

Construction work moves between the two, and one return has to carry both. Six months on a contractor’s books and six months subbing still means a single Self Assessment covering employment income, CIS income and the tax already taken under each.

Your personal allowance is counted once across the whole lot, not once per source. Where PAYE has already used part of it, or where nothing has used it at all, a flat CIS deduction can’t reflect that. The return is where the two get reconciled.

Two people working the same site can sit on different systems entirely. The payment statement tells you which one you’re on, not the job. The construction workers tax rebate guide covers the employed side.

Your CIS monthly statement is the key record

Your contractor has to give you a payment and deduction statement, and GOV.UK’s contractor guidance sets the deadline at 14 days after the end of each tax month. That CIS monthly statement is your evidence the tax was taken at all, and the figure you report on the return is built from it.

Alongside them you’ll want records of any employment income, any other income, and the costs you’re claiming. Allowable expenses on your CIS tax return covers which costs qualify, and what information do I need sets out the paperwork side.

If statements haven’t turned up, chase the contractor well before the filing deadline rather than the week of it.

Deadlines your CIS tax return has to meet

The dates are the ordinary Self Assessment ones. GOV.UK lists 5 October to register if the return is your first, 31 October for a paper return and 31 January for an online one, with any tax owed also due on 31 January.

Missing them doesn’t cancel a refund, though it does start a penalty running from day one. CIS tax return penalties covers how the ladder climbs.

Subcontractors inside Making Tax Digital for Income Tax file four quarterly updates a year through compatible software. Quarterly updates don’t replace the tax return. Your return still goes in at the year end, filed through the software as a final declaration rather than through the old Self Assessment route.

Qualifying income is the test, meaning gross self-employment and property income before expenses, taken from the return already filed for the year before.

Over £50,000 on the 2024/25 return brought you in from 6 April 2026. Over £30,000 on the 2025/26 return applies from April 2027, and over £20,000 on the 2026/27 return from April 2028.

Older years aren’t necessarily gone. Once the window for amending a return has closed, overpaid tax comes back through overpayment relief instead, and HMRC has to receive that claim no more than four years after the tax year in question ended. There’s more on the time limits in how far back can I claim a tax rebate.

Stopped trading? Claim your CIS tax refund sooner

Waiting until after 5 April isn’t the only option. Stop trading part-way through a tax year and an in year CIS tax refund becomes possible, where deductions already taken since the previous 6 April can be repaid without waiting for the year to finish.

Sole traders make that CIS repayment claim on form CIS40. Partners use form CIS41.

GOV.UK hedges this one. Its guidance says you “may be able to” claim, which is not the same as will, so treat it as an option rather than a certainty. Stopping work part-way through the year opens the door; HMRC still decides.

An in-year claim doesn’t replace the annual return either. You still file for the year your work stopped, and any repayment already received goes onto it.

Before you claim your CIS tax refund

A CIS tax refund isn’t a bonus or a windfall. It’s the gap between a deduction taken from your payments and a bill worked out on your profit, and it closes when your return goes in.

Get your payment and deduction statements together, add up what was taken, total the costs you can evidence, and file. Sole traders and partners claim CIS tax back through Self Assessment. If you’ve stopped trading part-way through the year, CIS40 or CIS41 can bring the money forward instead of waiting.

Companies go through their payroll scheme instead, and the Corporation Tax route carries a penalty risk.

The CIS tax rebate calculator gives you a rough figure to work with before you start.

Key Takeaways

• CIS deductions are advance payments towards your tax, worked out on your invoice after VAT and materials come off rather than on your profit, which is why the two figures rarely match.
• Three rates apply: 20% for registered subcontractors, 30% where you aren’t registered or can’t be verified, and 0% with gross payment status.
• Registering is what moves you off the 30% rate and onto the standard 20%.
• Sole traders and partners claim through Self Assessment; limited companies claim through their payroll scheme instead.
• Stopping trading part-way through a year lets you claim in-year on form CIS40, or CIS41 if you’re a partner.
• Overpayment relief runs out four years after the end of the tax year it relates to.