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How to Claim a CIS Refund, A Step-by-Step Guide for UK Subcontractors
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How to Claim a CIS Refund: Every Step, Deadline and Delay Explained
If contractors have been taking 20% off your invoices all year, you are almost certainly owed money back. Under the Construction Industry Scheme, or CIS, that deduction is not your final tax bill. It is an advance payment towards it, and it is nearly always more than you end up owing.
You claim the difference by filing a Self Assessment tax return after 5 April. There is no separate CIS refund form and no number to ring. The return is the claim.
That catches people out every year. What follows is the full process: when you can claim, what you need in front of you, how much to expect, and the five things that stop a repayment reaching your bank.
What a CIS refund actually is
Contractors in construction must deduct tax from the labour part of your payments and send it to HMRC on your behalf. The rate depends on your registration status.
| Your status | Deduction taken from your labour |
|---|---|
| Registered as a subcontractor | 20% |
| Not registered, or HMRC cannot verify you | 30% |
| Holding gross payment status | 0% |
Rates shown for the 2026/27 tax year. Two things make an overpayment almost inevitable.
The deduction comes off your gross labour income, so none of your expenses have reduced it yet. And it takes no account of your personal allowance, the slice of income you can earn tax-free.
Put those together and a subcontractor who has worked a full year has usually handed HMRC several thousand pounds more than the eventual bill. A Construction Industry Scheme refund is that overpayment coming back.
One detail worth knowing now: the deduction should only apply to labour. Materials, plant hire, consumable stores and VAT all come out of the calculation first. A contractor who applies 20% to your whole invoice has taken too much, which is recoverable but messy.
If you are not certain the scheme covers your work at all, start with what CIS is and who it applies to. Some jobs that sound like construction sit outside it, including carpet fitting and scaffolding hire supplied without labour. HMRC sets out the scope in its guidance on the Construction Industry Scheme.
When you can claim, and why you cannot do it mid-year
The UK tax year runs 6 April to 5 April. As a sole trader, you cannot reclaim deductions for a year that has not finished, because HMRC has no way to work out what you owe until it knows your full profit for the year.
The timetable for a CIS refund for subcontractors is fixed by the tax year, not by when you ask for it. A CIS tax refund follows the same UK calendar whether you are working in Ipswich or Inverness.
| Date | What it means for the 2026/27 tax year |
|---|---|
| 6 April 2027 | Earliest date you can file and claim |
| 5 October 2027 | Register for Self Assessment by here if 2026/27 was your first year of trading |
| 31 October 2027 | Paper return deadline |
| 31 January 2028 | Online filing deadline, and the date any balance is due |
File in the first week of April, not the following January. HMRC is processing far lower volumes in spring, and you have your money roughly nine months earlier than the subcontractor who waits for the deadline.
Filing early does not bring forward the date you have to pay if you owe tax. It only brings forward your refund.
The documents you need before you start
Almost every delayed claim traces back to a missing payment and deduction statement.
Every contractor who deducts CIS from you must give you a statement within 14 days of the end of each tax month. Tax months end on the 5th, so statements are due by the 19th. They are not a favour, and a contractor who will not produce them has a compliance problem of their own.
- Your ten-digit Unique Taxpayer Reference
- A payment and deduction statement from every contractor who paid you during the year
- Your own invoices, so you can prove the statements are complete
- Records of allowable expenses: tools, van, fuel, insurance, protective clothing, materials, phone, accountancy fees
- Any other income for the year, including employment, savings and property
- The bank account you want the repayment paid into
If a statement is missing, ask the contractor. Where they will not produce one, HMRC can accept your invoices and bank statements showing the net amount received, but expect the claim to take longer and to be looked at more closely.
How to claim a CIS refund step by step
You claim back CIS deductions through the same return you use to declare your profit. The mechanics are identical for a sole trader and for a partner in a partnership.
- Register for Self Assessment if you have not already. You need a Unique Taxpayer Reference before you can file and it takes time to arrive, so do not leave this until January.
- Total your income using gross figures, taken from your invoices before any deduction. This is the step people get wrong. Entering the net amounts you actually received understates your turnover, and it quietly understates your refund too.
- Total your allowable expenses for the year.
- Enter your CIS deductions in the right box. They belong on the trading pages of your return, form SA103S if you use the short version or SA103F if you use the full one. It is the box for deductions taken by contractors under CIS, not the general box for tax already paid on other income.
- Check the calculation. The return works out income tax and Class 4 National Insurance, sets your CIS deductions against the total, and shows a balance either owed or repayable. HMRC explains the filing process in its Self Assessment guidance.
- Submit, then tell HMRC where to send the money. You nominate a bank account through your online account. Without it, the repayment often sits as a credit on your record instead of being paid out.
Be careful who you sign with. Some refund firms use a deed of assignment, which redirects the repayment to them rather than to you, and it can bind future tax years as well as the one you engaged them for. Read the paperwork before you sign it.
How much do you get back? A worked example
Liam is a self-employed groundworker. In the 2026/27 tax year he invoiced £48,000, of which £6,000 was materials he bought and recharged. His contractors deducted 20% from the £42,000 of labour.
| Item | Amount |
|---|---|
| Turnover invoiced | £48,000 |
| Materials recharged, outside the deduction | £6,000 |
| Labour subject to CIS deduction | £42,000 |
| CIS deducted at 20% | £8,400 |
| Allowable expenses, including the £6,000 of materials | £11,500 |
| Taxable profit | £36,500 |
| Personal allowance, 2026/27 | £12,570 |
| Income tax at 20% on £23,930 | £4,786 |
| Class 4 National Insurance at 6% on £23,930 | £1,435.80 |
| Total liability | £6,221.80 |
| Less CIS already deducted | £8,400 |
| Refund due | £2,178.20 |
Run your own figures through the CIS refund calculator before you file, so nothing in the final number is a surprise.
Why your refund is smaller than the deductions on your statements
Liam had £8,400 taken and got £2,178.20 back. Nothing went wrong. The deduction was never a separate tax that gets returned in full; it was an advance against a bill of £6,221.80.
Four things close the gap between the two numbers.
- Your profit is still taxable. Expenses reduce your profit and increase your refund, but they cannot remove the tax on what is left. Claiming everything you are entitled to remains the biggest lever you actually control, and the allowable expenses calculator is a faster check than reading through HMRC’s lists.
- Class 4 National Insurance. Your CIS deductions are set against income tax and Class 4 together. National Insurance comes out of the same pot before anything is repaid to you.
- Student loan repayments. On any repayment plan, these are collected through Self Assessment and come off the refund. This one blindsides people every year.
- Payments on account. Taxpayers with a balancing bill over £1,000 usually have to make advance payments towards the next year. Subcontractors often avoid them, because payments on account are not required where 80% or more of your tax was already collected at source, which CIS deductions frequently are. Where you do owe them, HMRC will set your refund against them before paying anything out. That is why some April filers see a return marked as repayable and never see the cash.
Claiming CIS deductions through a limited company
The route is completely different, and getting it wrong can cost you a year.
A limited company never reclaims CIS through anybody’s Self Assessment. A director cannot put the company’s deductions on their personal return. The company reports the deductions it has suffered on an Employer Payment Summary through its payroll, and HMRC sets those against the PAYE, National Insurance and CIS the company owes for the same tax year. Any surplus left after 5 April is claimed as a repayment.
Here is the trap. A company with no PAYE scheme cannot file an Employer Payment Summary, so it has nowhere to report the deductions at all. Single director companies taking dividends only run into this constantly, and the deductions sit with HMRC unclaimed.
CIS deductions also never belong on the Corporation Tax return. If a set of accounts shows a CIS debtor carried forward for two years running, something has not been filed.
If you are weighing up incorporating, price this administration in first. Our limited company setup and compliance page covers what changes.
Why CIS refunds get delayed, and how to stop it
The most common cause of a stalled Construction Industry Scheme refund is a mismatch you cannot see.
Every month your contractors file a CIS300 return telling HMRC what they paid you and what they deducted. HMRC checks your claim against those returns. If a contractor filed late, quoted an old Unique Taxpayer Reference, or entered your trading name slightly differently, HMRC’s record shows less deducted than you have claimed, and your repayment drops into manual review.
- Reconcile every statement against your invoices before you file. If the totals disagree, find out why in April rather than in August.
- Give contractors your exact registered name and reference, and tell them promptly when either changes.
- If you are being deducted at 30%, you are either not registered or not verified. Fix the registration and future payments drop to 20%.
- Add your bank details to your HMRC online account before you submit, not after.
- Expect checks. HMRC selects repayment claims for verification, and a large first claim draws more attention than a routine one. Having your statements scanned and ready to send shortens it considerably.
If losing a fifth of every invoice at source is a permanent feature of your cash flow, gross payment status is the structural fix rather than reclaiming the money a year later. There are turnover, business and compliance tests to pass first.
Can you claim a CIS refund for an earlier year?
Yes, within limits.
Where the return for that year is already filed, you can amend it up to 12 months after the 31 January filing deadline. A 2025/26 return filed by 31 January 2027 can therefore be amended until 31 January 2028.
Once that window shuts, you claim through overpayment relief instead, which runs for four years from the end of the tax year concerned. Overpayment relief needs a written claim in a set form, not simply a revised return.
If you have never filed at all for a year in which CIS was deducted, file it. Late filing penalties may apply, but the refund frequently exceeds them, and leaving the return unfiled does not make the penalties any smaller.
What to do next
Whether your refund is quick or painful comes down to one thing: whether your payment and deduction statements reconcile to your invoices. Sort that before 6 April and the return itself is an evening’s work.
Get the statements into one folder, check the totals against what you invoiced, and run the numbers so you know what you are expecting. If you would rather hand the whole thing over, our tax return and CIS refunds service covers the claim and the reconciliation with your contractors.
This article is general information on how to claim a CIS refund and is not personalised tax advice. Rates, thresholds and deadlines change every April, so check the position for the tax year you are actually filing.
Most subcontractors are not short of a claim. They are short of paperwork, and that is a problem you can fix in a weekend.
Frequently Asked Questions About CIS Refunds
How do I claim a CIS refund as a subcontractor?
Most self-employed subcontractors claim CIS deductions through their Self Assessment tax return after the tax year ends. Enter your gross income, allowable expenses and the CIS deductions shown on your payment and deduction statements.
How much CIS refund will I get?
Your refund depends on your total income, allowable expenses, CIS deductions and other tax liabilities. CIS deducted at 20% is not automatically refunded in full. HMRC first uses it against your Income Tax and National Insurance liability.
Can I claim a CIS refund without payment and deduction statements?
If a CIS statement is missing, ask the contractor for a replacement first. If you cannot obtain one, contact HMRC. They may ask for other evidence, such as invoices and bank statements, to verify the payments and CIS deductions claimed.
How does a limited company claim back CIS deductions?
A limited company does not claim CIS deductions through a director’s Self Assessment or Corporation Tax return. CIS suffered by the company is normally reported through payroll using an Employer Payment Summary and set against relevant PAYE liabilities.
Can I claim CIS deductions from a previous tax year?
Yes, subject to HMRC’s time limits. You can normally amend a Self Assessment return within 12 months of the filing deadline. After that, overpayment relief may be available within four years from the end of the relevant tax year, subject to HMRC’s rules.
