This article was written with the help of AI.
Under the Construction Industry Scheme, a contractor deducts 20% from a registered subcontractor's labour payments and 30% from an unregistered one [1]. Those deductions are only advance payments towards the subcontractor's tax [2], so whenever they exceed the final bill the difference is a CIS tax refund.
The scheme deducts at a flat rate from gross labour income, before any expenses or personal allowance are taken into account. A self-employed bricklayer, electrician or plasterer who buys tools, runs a van and pays for insurance will often have had far more tax withheld across the year than the profit actually justifies. The same mechanism hits limited companies working as subcontractors, which can end a tax year holding deductions they could not use against their own payroll liabilities.
The route to the money depends on the legal form of the business. Sole traders and partners reclaim through Self Assessment, limited companies offset deductions in real time through their payroll submissions and claim any balance after the tax year ends, and a handful of special cases (stopping trading, liquidation, a switch to gross payment status) allow an in-year claim. This guide sets out each route, the evidence HMRC expects, the reforms that took effect from 6 April 2026, and the reconciliation habits that keep a claim from stalling.
Key takeaways
- CIS deductions are taken at 20% (registered) or 30% (unregistered) from the labour element of a payment, never from VAT or materials.
- Sole traders and partners recover overpaid deductions through their Self Assessment return; an in-year claim on form CIS40 or CIS41 is possible only after trading stops.
- Limited companies set CIS deductions suffered against their own PAYE, National Insurance, student loan and CIS liabilities through the Employer Payment Summary, then claim any unused balance once the tax year ends.
- HMRC usually responds to a limited company refund claim within 8 weeks, provided every FPS, EPS, CIS and Company Tax return is already filed.
- Monthly payment and deduction statements are the backbone of every claim, because HMRC matches the claim against what contractors reported.
Why CIS refunds arise in the first place
The Construction Industry Scheme sets out how contractors handle payments to subcontractors for construction work, with deductions passed straight to HMRC [22]. HMRC's own manual describes the scheme as a set of rules under which payments by contractors to subcontractors are made with or without a deduction, depending on the subcontractor's registration status [25]. The structural point is that the deduction is a withholding mechanism, not a tax calculation.
The deduction is calculated on gross labour, not on profit
A contractor works out the deduction on the invoice total after removing VAT, consumable stores, fuel (other than for travel), plant hire, manufactured or prefabricated materials, and materials the subcontractor paid for directly [11]. The deduction rate then applies to what is left. Business costs such as tools, protective clothing, vehicle running costs, insurance and accountancy fees are not deducted at this stage, even though most of them are allowable expenses when the subcontractor's profit is calculated [21].
The three deduction rates are set out below [1].
| Subcontractor status | Deduction on labour | Typical refund position |
|---|---|---|
| Registered for CIS and verified by the contractor | 20% | Refund likely where expenses are significant or income is modest |
| Not registered, or cannot be verified | 30% | Refund very likely, often large |
| Gross payment status | 0% | No CIS refund; tax and NI paid at year end |
Personal allowance and expenses widen the gap
A sole-trader subcontractor is taxed on profit, after allowable expenses, and only on the part of that profit above the £12,570 Personal Allowance [16]. A flat 20% deduction from the first pound of labour income ignores both, which is why the Low Incomes Tax Reform Group notes that refunds typically arise where income is lower, because of trading expenses and personal allowances [10]. The CIS340 guide confirms that where the amounts deducted exceed the amount due, HMRC repays the excess [15].
Class 4 National Insurance has to be covered from the same pot. For the 2026-27 tax year, Class 4 is charged at 6% on profits between £12,570 and £50,270 and 2% above that, with Class 2 treated as paid once profits reach £7,105 [17]. The refund is whatever remains of the CIS deductions once income tax and Class 4 are settled.
How a sole trader claims a CIS tax refund
For a self-employed individual, the Self Assessment return is the claim. At the end of the tax year, the subcontractor records total pay before deductions as income and the total deductions in the box for CIS deductions [2]. If the deductions exceed the liability, HMRC pays back the difference; if they fall short, the balance is due by 31 January after the tax year ends.
Which form, and which boxes
Individual traders report CIS deductions on the short or full self-employment pages (SA103S or SA103F), while partnerships use the partnership return SA800 and each partner's SA104S or SA104F [15]. CIS deductions must not be entered on the employment pages. Anyone earning more than £1,000 from self-employment must file a return in any case [26], so almost every CIS subcontractor is already inside Self Assessment.
The table below summarises the main return deadlines [13].
| Filing route | Deadline after the tax year ends (5 April) |
|---|---|
| Paper return | 31 October |
| Online return | 31 January |
| Online return, to have a debt collected through the tax code | 30 December |
| Payment of any balance owed | 31 January |
Online returns can be sent from 6 April onwards [13], and filing early is the single most effective way to accelerate a refund. Waiting until January simply leaves money with HMRC for longer. A late return attracts an initial £100 penalty even where no tax is owed [19], which can wipe out part of a modest refund.
A worked example
Consider a registered subcontractor with £30,000 of labour income (materials already stripped out) in the 2026-27 tax year. The contractor withheld 20%, so £6,000 of deductions appear on the monthly statements [1]. The subcontractor also incurred £6,000 of allowable costs on tools, van running and insurance [21], leaving a taxable profit of £24,000.
The final liability for the year is set out below, using the 2026-27 income tax bands and Class 4 rates [16] [17].
| Line | Amount |
|---|---|
| Profit above the £12,570 Personal Allowance | £11,430 |
| Income tax at 20% on that slice | £2,286 |
| Class 4 NI at 6% on that slice | £685.80 |
| Total liability | £2,971.80 |
| CIS deductions suffered | £6,000 |
| Refund due | £3,028.20 |
More than half of the money withheld by contractors comes back. Had the same subcontractor been unregistered, the 30% rate would have withheld £9,000 instead [1], pushing the refund above £6,000 but leaving the extra cash with HMRC until the return is processed. Registering for CIS before starting work is the cheapest cash-flow improvement available [28].
Payments on account and the 80% rule
HMRC normally asks Self Assessment taxpayers to make two advance payments towards the next year's bill, but not where more than 80% of the tax owed has already been paid at source or the previous bill was under £1,000 [20]. Because CIS deductions count as tax paid in advance [2], most subcontractors on the standard rate fall outside payments on account altogether. A subcontractor whose business shifts towards private householders (who are outside CIS) can lose that protection and face a payments-on-account demand on top of the balancing payment.
In-year claims: stopping trading, partners and CIS40
The default rule is that individuals wait for the tax year to end. Form CIS40 lets a self-employed subcontractor claim a repayment of deductions during the current tax year, but HMRC treats it as an exception: after the tax year ends, the return is used instead [4]. Partners use the equivalent form CIS41.
When CIS40 or CIS41 can be used
GOV.UK limits the in-year route to a sole trader or partner who stops trading, allowing a refund of deductions already taken in the current tax year [2]. LITRG adds that the work must have ceased and all tax affairs must be up to date, and that the Self Assessment return for the year still has to be filed, recording the CIS40 refund as a refund already received [10]. The form is available through the online forms service, or can be printed, completed in full and posted [4].
| Claimant | In-year form | Year-end route |
|---|---|---|
| Sole trader who has stopped trading | CIS40 | Self Assessment (SA103S or SA103F) |
| Partner in a partnership that has stopped trading | CIS41 | Partnership return SA800 plus SA104 pages |
| Limited company in liquidation or administration | Repayment claim | Limited company refund claim |
Agents that take a percentage
LITRG specifically warns about refund agents who charge a percentage of the repayment [10]. Where an agent receives a limited company's refund, HMRC requires a form R38 or a signed authority [3], and the subcontractor remains responsible for the accuracy of the return either way. Anyone using an adviser benefits from checking that fees are fixed rather than tied to the size of the refund.
How a limited company reclaims CIS deductions
Limited companies do not wait for the year end in the same way. A company subcontractor sends its Full Payment Submission as usual and, at the same time, an Employer Payment Summary showing total CIS deductions suffered for the year to date [2]. HMRC offsets those deductions against what the company owes and collects only the balance. This is where CIS meets payroll directly, and where HMRC-recognised payroll software for SMEs does most of the work.
Real-time offset through the EPS
The CIS340 guide states that a company sets CIS deductions against its own PAYE, National Insurance, student loan and CIS liabilities, monthly or quarterly, with any excess carried forward within the same tax year [15]. Where the deductions cover the whole liability for a period, the company tells HMRC in the EPS that nothing is payable [2]. There is no in-year cash repayment, except where the company is in liquidation or administration.
The table below shows a single month for a company subcontractor employing one member of staff on £2,500 a month, before any Employment Allowance [15].
| Payroll line for the month | Amount |
|---|---|
| Employee income tax (1257L) | £290.20 |
| Employee NI (category A) | £116.16 |
| Employer NI | £312.45 |
| Total PAYE and NI due | £718.81 |
| CIS deductions suffered (20% of £6,000 labour) | £1,200 |
| Excess carried forward | £481.19 |
If the pattern repeats every month, the company ends the year with £5,774.28 of unused deductions that only a year-end claim can release. Companies keep a record of deductions set off against PAYE, and HMRC provides form CIS132 for the purpose [2].
Claiming the unused balance after 5 April
Once the tax year (6 April to 5 April) has ended, the company can claim online or by post for any of the past 6 tax years; older years can only be claimed by post [3]. The overpayment is simply total CIS deductions less the tax already paid using those deductions, and an estimate is accepted if the exact figure is uncertain. HMRC says it will usually respond within 8 weeks [3].
The company can also ask for the refund to be used against Corporation Tax (giving the accounting period) or VAT (giving the VAT number and amount) rather than paid out [3]. What it must not do is use the Company Tax Return itself to settle tax with CIS deductions, which GOV.UK warns can lead to a penalty [2].
What the claim must contain
The limited company refund guidance lists the information HMRC needs before it will process a claim [3]. Since an update on 6 April 2026, every relevant return must be submitted first, which turns payroll housekeeping into a precondition of the refund [3].
| Item | Detail required |
|---|---|
| Company details | Name, telephone, address, PAYE reference, Corporation Tax UTR |
| Returns already filed | All FPS and EPS, monthly CIS returns if also a contractor, Company Tax returns |
| Bank details | Bank name, account number, sort code, account holder |
| Third-party payee | Form R38 or a signed authority |
| Current-year claims only | Copies of every payment and deduction statement and bank statement for the year |
A current-year claim is only possible where the business has stopped trading or deductions were taken after it moved to gross payment status [3]. HMRC's manual confirms that where a company entitled to gross or standard treatment suffered an incorrect deduction, the case is handled by the contractor's End of Year section and settled by manual repayment [12].
Payment and deduction statements: the evidence behind every refund
Every refund, whatever the claimant, rests on the monthly payment and deduction statement (PDS). A contractor must give one to every subcontractor from whom a deduction was made, within 14 days of the end of the tax month [9]. A tax month runs from the 6th of one month to the 5th of the next [7], so the statement for the month ending 5 June is due by 19 June [11].
What a valid statement shows
HMRC's manual sets out the required content [8]: the contractor's name and employer's tax reference, the tax month end date (or payment date for a one-off payment), the subcontractor's name and UTR, the verification number where the higher rate applied, the gross amount, the cost of materials and the amount deducted. Statements can be sent electronically only where both parties agree and the subcontractor can save and print them [9].
Why the statement alone is not enough
HMRC is explicit that the PDS is the subcontractor's receipt and cannot be used on its own to support a repayment claim [8]. Before accepting a claim, the statement must agree with the CIS system and with the contractor's CIS300 monthly return, and the checking procedures are set out separately in the manual [24]. If the contractor reported the wrong amount or filed late, the subcontractor's refund is held up, even though the subcontractor did nothing wrong.
Contractors must file the monthly return by the 19th of each month [23], and deductions are due to reach HMRC by the 19th, or the 22nd when paid electronically [7]. Where a statement is missing, the subcontractor can write to PT Operations at BX9 1BX with the contractor's details and the relevant tax months [1].
Reconciling statements against the bank
The limited company guidance notes that HMRC matches each claim against the information contractors supplied and, if the figures do not match, asks for statements and bank records [3]. If evidence does not arrive by the deadline HMRC sets, it amends the claim and the company cannot make further claims for that tax year, subject to a right of appeal [2]. A monthly three-way match (statement, CIS300 data where available, and bank receipt) is the practical defence. Payroll bureau software that stores each statement against the matching EPS line makes that match routine for accountants handling several construction clients.
Reforms from 6 April 2026 that affect refunds
Two packages of CIS changes took effect from 6 April 2026. Neither changes the refund mechanics directly, but both change the behaviour of the contractors whose data feeds every claim.
Administrative simplification
The simplification measure removes payments to local authorities and certain public bodies from the scope of CIS from 6 April 2026 [5], a change also reflected in the CIS340 guide [15]. It also reinstates nil returns: a contractor that pays no subcontractors in a month must file a nil return or tell HMRC in advance, or face a penalty without a reasonable excuse [5]. More complete contractor filing means fewer gaps when HMRC cross-checks a subcontractor's claim.
Fraud measures and gross payment status
The fraud package allows HMRC to cancel gross payment status immediately where a business knew, or should have known, that a transaction was connected to fraudulent evasion, and extends the reapplication bar from one year to 5 years [6]. A penalty of 30% of the lost tax can be charged to the business and its directors. A subcontractor that loses gross status starts suffering deductions again, and the gross payment status page sets out the compliance and turnover tests (£30,000 for a sole trader) needed to regain it [14]. The strengthened tests introduced from 6 April 2024 already added VAT compliance to the review [27]. More detail on the threshold sits in the guide to CIS gross payment status.
Making Tax Digital for sole-trader subcontractors
Separately from CIS itself, sole traders with qualifying income over £50,000 were brought into Making Tax Digital for Income Tax from 6 April 2026 [18]. For a subcontractor in scope, quarterly digital updates replace a single annual record dump, but the CIS refund is still settled through the end-of-year Self Assessment position [2]. Keeping statements digitally from the first month makes both obligations easier.
Common reasons a CIS refund is delayed
Most stalled refunds come down to mismatched data rather than disputed entitlement. The table below groups the usual causes with the source that governs each [3].
| Cause | Effect | Fix |
|---|---|---|
| Missing FPS, EPS, CIS or CT return | Limited company claim not processed | File every outstanding return before claiming |
| Contractor under-reported deductions | Claim figure does not match HMRC data | Obtain the PDS and ask the contractor to amend its CIS300 |
| Statements lost | No evidence when HMRC asks | Write to PT Operations, BX9 1BX |
| Deductions entered on the wrong SA pages | Self Assessment misreports the credit | Use SA103 or SA104, never the employment pages |
| Higher 30% rate applied by mistake | Larger overpayment and delay | Check verification status with the contractor |
HMRC's manual adds that deductions made outside a period of gross or standard-rate entitlement cannot be repaid immediately: for individuals they are set against tax and Class 4 NI for the accounting period, and for companies against PAYE, NI and CIS [12]. The contractor's End of Year section and the Self Assessment processing office each own a different part of the process [12], which is why a clear paper trail matters more than speed of submission.
Where payroll software fits in a CIS refund
For a limited company subcontractor, every pound of CIS deductions suffered is recovered through payroll first. An EPS that carries the correct year-to-date CIS figure each month is what turns a deduction into an offset, and an error carried for twelve months becomes an unexplained balance at the year end [2]. The broader mechanics of running payroll alongside the scheme are covered in CIS payroll explained.
Platforms that serve construction businesses, from job-costing tools to bookkeeping apps, can embed that logic rather than rebuild it. The HMRC-recognised payroll API from Moonworkers calculates PAYE and NI, submits the FPS and EPS, and records CIS deductions suffered so the year-to-date figure is always ready for the refund claim [15]. Sole traders who later incorporate can start with payroll for one-person businesses and keep the same records when the business grows. Year-end filing for individuals is set out in the guide to the CIS tax return.
Conclusion
A CIS tax refund is not a windfall. It is the scheme correcting itself, returning the difference between a flat withholding rate and the real liability on profit after expenses and allowances. The size of that difference depends on registration status, the share of materials in each invoice, and the level of business costs, all of which a subcontractor can shape before the first payment is made.
The administrative weight sits with evidence. With nil returns reinstated and HMRC requiring every PAYE, CIS and Corporation Tax return to be filed before a company claim is processed, refunds increasingly reward businesses whose monthly records already reconcile. Subcontractors and their accountants who treat each payment and deduction statement as a ledger entry, rather than a receipt to file away, are the ones who see their money back first.
Frequently asked questions
How long does a CIS tax refund take for a limited company?
HMRC says it will usually respond to a limited company refund claim within 8 weeks [3]. The clock only runs smoothly if every FPS, EPS, CIS return and Company Tax return is already filed and the claim matches the contractors' data. Mismatches trigger requests for statements and bank records, which add time, and if the evidence is not supplied by HMRC's deadline the claim is amended [2].
Can a self-employed subcontractor get a CIS refund before the tax year ends?
Only after stopping trading. A sole trader can then use form CIS40 and a partner form CIS41 to claim deductions taken in the current tax year [4]. Otherwise the refund comes through the Self Assessment return, which can be filed online from 6 April [13].
How far back can a limited company claim overpaid CIS deductions?
A limited company can claim online or by post for any of the past 6 tax years, and by post only for earlier years [3]. Each year can be claimed once it has ended, and the claim can be amended later if the overpayment figure changes. Deductions left unused within a tax year are carried forward through the EPS until that point [2].
Are CIS deductions taken from materials or VAT?
No. The deduction applies only to the labour element after removing VAT, consumable stores, plant hire, fuel other than for travel, and materials the subcontractor bought directly [11]. A contractor may ask for receipts to support the materials figure and will estimate it if none are provided [1].
