CIS Refund Form Explained

/Published:27th March 2026/inContractors, Freelancers, Sole Trader, Tax
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If you work in the construction industry as a subcontractor, tax is likely being deducted from your payments before you receive them. Under the Construction Industry Scheme (CIS), contractors are required by HMRC to deduct tax at source – either at 20% if you are registered for CIS, or 30% if you are not.

Because these deductions are calculated on your gross payments rather than your actual taxable profit, they often exceed the tax you truly owe. Once your allowable business expenses and personal tax allowances are taken into account, many subcontractors find they have overpaid and are entitled to a refund from HMRC.

This post looks at everything you need to know about claiming a CIS refund in 2026, including:

  • What the CIS refund form is and which form applies to you
  • Who is eligible to claim
  • How the refund is calculated
  • What documents and records you will need
  • Common mistakes that can delay or reduce your claim
  • How long refunds typically take to arrive

The Construction Industry Scheme is administered by HM Revenue and Customs (HMRC). It applies to most construction work carried out in the UK, covering both sole trader subcontractors and limited company subcontractors – though the refund process differs depending on your business structure.

Practical tip: CIS deductions are not a final tax charge. They are advance payments made toward your overall tax liability. If those deductions are greater than the tax you owe for the year, HMRC should refund the difference – but it is your responsibility to claim it.

If you are unsure whether you are owed money or how to begin a claim, speaking to a qualified accountant can save time and help ensure you recover the full amount you are entitled to.

What Is CIS?

The Construction Industry Scheme (CIS) is a tax deduction scheme operated by HMRC that governs how payments are made between contractors and subcontractors in the UK construction industry.

Under the scheme, contractors are legally required to deduct tax from payments made to subcontractors and pass those deductions directly to HMRC. This applies to the labour element of a payment – materials are generally excluded from the deduction calculation.

The standard CIS deduction rates are:

  • 20% – for subcontractors who are registered with HMRC under CIS
  • 30% – for subcontractors who are not registered
  • 0% – for subcontractors who hold gross payment status, meaning they receive payments in full and settle their own tax directly with HMRC

These deductions are not a final tax charge. They function as advance payments towards your tax liability for the year. When your Self Assessment tax return is submitted or, for limited companies, when your Corporation Tax position is confirmed – HMRC calculates what you actually owe. If your CIS deductions exceed that figure, you are due a refund.

Practical tip: If you are currently unregistered and having 30% deducted, registering for CIS with HMRC will reduce your deduction rate to 20% immediately. This can make a significant difference to your cash flow throughout the year. You can register on the GOV.UK CIS registration page.

CIS applies to most construction work in the UK, including new builds, alterations, repairs, demolition, and civil engineering projects. Some work is exempt including architecture, surveying, scaffolding hire without labour, and carpet fitting. You can find a full breakdown of what is and is not covered in HMRC’s Construction Industry Scheme guidance on GOV.UK.

What Is a CIS Refund?

A CIS refund occurs when the tax deducted from your payments by contractors during the tax year is greater than your actual tax liability once your full financial position is assessed.

This overpayment happens because CIS deductions are calculated on your gross income before any business expenses or personal allowances are taken into account. In practice, most subcontractors have legitimate costs that reduce their taxable profit considerably, which means the deductions made throughout the year often exceed what they genuinely owe.

Common expenses that reduce your taxable profit and therefore increase the likelihood of a refund include:

  • Tools, equipment, and protective clothing
  • Vehicle costs and mileage for business travel
  • Public liability insurance
  • Phone and communication costs used for work
  • Accountancy fees
  • Materials purchased for jobs (where not already reimbursed)

The difference between what was deducted and what you actually owe is the amount HMRC should refund to you. How you reclaim that difference depends on your business structure:

  • Sole traders and partnerships – the refund is generated through your annual Self Assessment tax return. HMRC calculates your liability based on your income and expenses, credits your CIS deductions against that figure, and refunds any surplus.
  • Limited companies – CIS deductions are offset against the company’s monthly PAYE and National Insurance liabilities. Any remaining credit can be reclaimed separately after the Corporation Tax return is processed.

Practical tip: Even subcontractors on the higher 30% unregistered rate can claim a CIS refund. Registering for CIS reduces future deductions to 20%, but it does not prevent you from reclaiming overpayments already made. Accurate records of your income and expenses are the key to maximising your legitimate refund.

It is important to note that CIS refunds do not arise automatically. You must actively claim by submitting the appropriate return or form to HMRC. Failing to do so means overpaid tax simply remains with HMRC.

Is There a Specific CIS Refund Form?

This is one of the most common points of confusion around CIS refunds. There is no single standalone form that applies to everyone. The process you follow and the form you use – depends on how your business is structured.

Sole Traders and Self-Employed Subcontractors

The majority of subcontractors claim their CIS refund through the Self Assessment tax return. You declare your income and allowable expenses for the tax year, and HMRC credits your CIS deductions against your calculated tax liability. If the deductions exceed what you owe, the balance is refunded.

If you have stopped working in the construction industry during the current tax year and need to claim a refund before the year ends, you may be able to use form CIS40 – available on GOV.UK. This allows individuals to claim repayment of subcontractor deductions in-year, rather than waiting until after 5 April.

If you are a partner in a partnership, a separate form – CIS41 – is used to claim a partner’s repayment of subcontractor deductions.

Limited Companies

Limited company subcontractors do not use the Self Assessment process. Instead, CIS deductions are offset against the company’s PAYE and National Insurance liabilities each month. Where deductions exceed those liabilities, the company can reclaim the surplus using HMRC’s online CIS repayment form – accessed via the Government Gateway or by writing to HMRC by post.

Employees Paid Under PAYE

In some cases, a worker may have been incorrectly treated as a CIS subcontractor when they should have been employed under PAYE. Where tax has been overpaid as a result, a refund may be reclaimed using form R38, or by contacting HMRC directly to request a repayment.

Practical tip: If you are a sole trader who has been working under CIS throughout the year, filing your Self Assessment tax return promptly after 5 April is the most straightforward route to your refund. HMRC has a four-year time limit for claiming overpaid tax, so do not leave previous years unchecked if you think you may have overpaid.

The table below summarises which route applies to each business type:

Business TypeRefund Route
Sole trader / self-employedSelf Assessment tax return (or CIS40 for in-year claims)
PartnershipSelf Assessment tax return (or CIS41 for in-year claims)
Limited companyPAYE offset, then HMRC online form or postal claim
Employee (incorrectly on CIS)Form R38 or direct HMRC repayment request

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How CIS Refunds Work for Sole Traders

If you operate as a sole trader under CIS, you claim your refund through the Self Assessment tax return system. The process requires you to declare your total income, your allowable business expenses, and the CIS tax that was deducted from your payments during the tax year. HMRC then calculates your actual tax liability and refunds any overpayment.

The steps involved are:

  1. Register for Self Assessment with HMRC if you have not already done so
  2. Gather your CIS deduction statements, income records, and expense receipts for the tax year
  3. Submit your Self Assessment tax return, declaring your total CIS income, allowable expenses, and the total CIS tax deducted
  4. HMRC credits your CIS deductions against your tax bill – if deductions exceed what you owe, the difference is refunded

Example: Sole Trader CIS Refund

The following example illustrates how a typical CIS refund is calculated for a sole trader:

  • Total CIS income received: £40,000
  • CIS deductions made by contractors at 20%: £8,000 paid to HMRC
  • Allowable business expenses: £15,000
  • Taxable profit (£40,000 minus £15,000): £25,000
  • Actual Income Tax and National Insurance due on £25,000: £5,500
  • CIS already paid to HMRC: £8,000
  • Refund due: £2,500

Practical tip: The more thoroughly you record your allowable expenses, the closer your CIS deductions will be to or above your actual tax liability. Keeping accurate records throughout the year, rather than reconstructing them at return time, makes a material difference to the size of a legitimate refund.

What Documents Do You Need?

Before submitting your CIS refund claim, you should gather the following:

  • CIS deduction statements – provided by each contractor you worked for, showing gross payment, deductions made, and net payment received
  • Income records – invoices or payment records for all CIS work carried out during the year
  • Expense receipts – receipts or evidence for all business costs you intend to claim
  • Your Unique Taxpayer Reference (UTR) – required to file Self Assessment and to be verified by contractors
  • Your National Insurance number

CIS deduction statements are particularly important. If your declared deductions do not match the figures held by HMRC – submitted monthly by your contractors – your claim may be delayed or queried. Request statements promptly from every contractor you have worked with during the year and check them carefully against your own records.

What About Limited Companies?

The process for limited company subcontractors is distinct from the sole trader route and involves two separate mechanisms.

Each month, the company can offset its CIS deductions suffered against the PAYE tax and National Insurance it owes to HMRC as an employer. This is reported via the Employer Payment Summary (EPS), which reduces the monthly PAYE payment due. If the CIS deductions for the month exceed the PAYE liability, the excess can be carried forward or reclaimed directly from HMRC.

Where a refund is due, the company can claim using HMRC’s online CIS repayment form via the Government Gateway, or by writing to HMRC by post, marking the correspondence clearly as a CIS claim. The company’s Corporation Tax return will also reflect CIS deductions suffered for the year.

Practical tip: Limited companies should submit their CIS repayment claim after the 5 April filing deadline to ensure all deduction records for the previous tax year are captured. Submitting too early may result in incomplete records, causing delays or an incorrect payment.

When Can You Claim a CIS Refund?

For sole traders, CIS refunds are typically claimed after the end of the tax year, which runs from 6 April to 5 April the following year. The Self Assessment tax return for a given year must be submitted online by 31 January following the end of that tax year.

Submitting your return as early as possible after 6 April – rather than waiting until January – generally results in a faster refund, as HMRC processes returns in the order they are received and earlier submissions face less seasonal demand.

If you have stopped working in construction during the current tax year and cannot wait until the year end, form CIS40 may allow you to make an in-year claim. HMRC has a four-year time limit for reclaiming overpaid tax, so it is worth reviewing previous years if you believe you may not have claimed your full entitlement.

How Long Does a CIS Refund Take?

Processing times vary depending on the complexity of your claim and whether HMRC needs to verify any information. As a general guide:

  • Straightforward returns – typically processed within two to six weeks of submission
  • Returns requiring review – can take longer if HMRC requests supporting documentation or identifies a discrepancy

Refunds are more likely to be delayed where:

  • CIS deduction figures do not match the amounts submitted by your contractors
  • CIS deduction statements are missing or incomplete
  • UTR details are incorrect or your Self Assessment record is not up to date
  • The claim is submitted before all contractor monthly returns for the year have been processed

If you have been waiting more than 40 working days for a refund, contact HMRC’s CIS helpline to follow up on your claim.

Common CIS Refund Mistakes

The following errors are among the most frequently seen when subcontractors attempt to claim CIS refunds, and each carries the risk of delaying your repayment or triggering a compliance check from HMRC:

  1. Not registering for Self Assessment – you cannot claim a CIS refund without being registered, and late registration can result in penalties
  2. Failing to include all allowable expenses – overlooking legitimate costs means you pay more tax than necessary
  3. Losing or not requesting CIS deduction statements – without these, your declared figures may not match HMRC’s records
  4. Using unverified refund agents – some third-party services inflate claims or charge excessive fees; see the section below
  5. Failing to declare all income – HMRC cross-references contractor submissions, so undeclared income is likely to be identified
  6. Mismatched figures between contractor and subcontractor records – even small discrepancies can flag a return for manual review

Practical tip: HMRC receives monthly CIS returns from every contractor you work for. The figures they hold are checked against your Self Assessment submission. Accuracy and consistency between your records and your contractors’ records is the single most effective way to avoid delays.

Beware of CIS Refund Specialists

A number of firms advertise themselves as CIS refund specialists, often promising large or guaranteed repayments. While there are legitimate tax agents who can assist with CIS claims, you should approach any such service with caution if they:

  • Promise unusually high refunds without reviewing your actual records
  • Charge commission based on a percentage of your refund – sometimes 30% or more
  • Submit returns on your behalf without providing you with a copy to review
  • Encourage you to claim expenses you cannot evidence or did not genuinely incur

It is important to understand that you remain legally responsible for the accuracy of your tax return, regardless of who prepares it. If HMRC investigates a return and finds inflated or fictitious claims, any penalties and underpaid tax will be pursued from you – not the agent. Working with a qualified, regulated accountant is the safest route to a legitimate and accurate claim.

What If You Hold Gross Payment Status?

Subcontractors who have been approved for gross payment status by HMRC receive their payments in full, with no CIS deductions made at source. This status is granted to those who meet HMRC’s compliance and turnover tests.

If you hold gross payment status, you still need to complete a Self Assessment tax return and pay any tax and National Insurance due. Because no deductions are taken upfront, refunds are less common – though they can still arise if your business expenses result in a lower tax liability than your advance payments on account.

You can find out more about applying for gross payment status on GOV.UK.

Can Employees Claim CIS Refunds?

CIS applies specifically to self-employed subcontractors. If you are engaged as an employee and paid through PAYE, CIS deductions should not apply to your payments. If tax has been incorrectly deducted under CIS when you should have been treated as an employee, you may be entitled to reclaim the overpayment but the process will differ from a standard CIS refund claim. In these circumstances, contacting HMRC directly or speaking with an accountant is advisable.

It is worth noting that employment status in construction is a complex area. HMRC may challenge arrangements where individuals are treated as subcontractors but whose working patterns resemble employment. If you are unsure of your status, HMRC’s employment status guidance is a useful starting point.

Tips to Maximise Your CIS Refund

Maximising your CIS refund legitimately comes down to thorough record-keeping and claiming every expense you are genuinely entitled to. The following steps make a real difference:

  • Keep detailed expense records throughout the year – do not rely on memory or bank statements alone; retain receipts and invoices as you go
  • Track business mileage – record every work-related journey, including date, destination, and purpose; HMRC’s approved mileage rate for cars is currently 45p per mile for the first 10,000 miles
  • Claim tool and equipment purchases – tools bought wholly for work are an allowable expense
  • Include insurance costs – public liability and other business insurance premiums are deductible
  • Claim training and professional development costs – where relevant to your existing trade
  • Consider home office costs – if you manage your business administration from home, a proportion of relevant costs may be claimable
  • Reconcile your CIS statements monthly – checking deduction statements against your own records as you receive them prevents discrepancies building up by year end

Practical tip: Good bookkeeping is not just about compliance – it directly increases the refund you can legitimately claim. Subcontractors who maintain organised records consistently recover more of their overpaid tax than those who reconstruct their finances at the last minute.

Final Thoughts

A CIS refund is not a windfall or a bonus from HMRC. It is simply the return of tax you have already paid in advance – money that was deducted from your payments before you ever received it. Because those deductions are calculated on gross income rather than taxable profit, overpayment is the norm for most subcontractors, not the exception.

Claiming that money back is a straightforward process when approached correctly. The fundamentals are consistent regardless of your business structure:

  • Register for Self Assessment if you are a sole trader or partner, and do so as early as possible
  • Collect and retain your CIS deduction statements from every contractor you work with throughout the year
  • Record all allowable business expenses as they arise, with receipts and evidence to support each one
  • Submit accurate, complete returns that reflect your actual income and costs and reconcile your figures against contractor submissions before filing

Handled properly, CIS refunds can make a meaningful difference to cash flow – particularly in trades where materials, equipment, vehicle costs, and insurance represent a significant proportion of annual outgoings. The higher your legitimate expenses, the greater the gap between the tax deducted and the tax you actually owe.

The two factors that consistently delay or reduce refunds are poor record-keeping and inaccurate returns. Both are avoidable. Maintaining organised records throughout the year, requesting deduction statements promptly, and filing on time removes most of the friction from the process.

Practical tip: If you are unsure whether you have claimed your full entitlement or if you have not filed returns for previous years HMRC allows overpaid tax to be reclaimed going back four tax years. It is worth reviewing earlier years before that window closes.

If you work under CIS and would like help ensuring your records are in order, your return is accurate, and you are recovering everything you are legitimately owed, speak to the team at Accounting Wise. We work with sole traders, partnerships, and limited companies across the construction industry and can manage the entire process on your behalf.

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CIS Refund Form FAQ

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A CIS refund is a repayment from HMRC when the tax deducted from your construction payments by contractors exceeds your actual tax liability for the year. Because deductions are taken from your gross income rather than your taxable profit, overpayment is common among subcontractors.

Sole traders claim CIS refunds through the Self Assessment tax return. You declare your total CIS income, allowable business expenses, and the tax deducted by your contractors. HMRC calculates your liability and refunds any surplus. Returns must be submitted online by 31 January following the end of the tax year.

Limited companies offset CIS deductions against their monthly PAYE and National Insurance liabilities using the Employer Payment Summary (EPS). Where deductions exceed those liabilities, the company can reclaim the difference using HMRC’s online CIS repayment form via the Government Gateway, or by writing to HMRC by post.

There is no single form that applies to everyone. Sole traders claim through Self Assessment, while those who have stopped working in construction during the current tax year may use form CIS40 for an in-year claim. Partners use form CIS41. Limited companies use the HMRC online repayment form or a postal claim marked as CIS.

Straightforward claims are typically processed within two to six weeks of submission. Refunds can take longer if HMRC needs to verify documentation, if CIS deduction figures do not match contractor submissions, or if returns are filed before all contractor monthly records have been processed. If you have been waiting more than 40 working days, contact HMRC’s CIS helpline.

HMRC allows overpaid tax to be reclaimed going back four tax years. If you have not filed returns for previous years or believe you may not have claimed your full entitlement, it is worth reviewing earlier years before that window closes.

You will need CIS deduction statements from every contractor you worked for during the year, your income records, receipts for allowable business expenses, your Unique Taxpayer Reference (UTR), and your National Insurance number. CIS deduction statements are particularly important as HMRC cross-references these against contractor submissions.

Yes. Unregistered subcontractors have tax deducted at 30% rather than the standard 20%, but they are still entitled to claim a refund if their deductions exceed their tax liability. Registering for CIS with HMRC will reduce future deductions to 20% and improve your cash flow going forward, but it does not affect your right to reclaim overpayments already made.

Glossary of Key CIS Terms

CIS (Construction Industry Scheme) – A tax deduction scheme operated by HMRC requiring contractors to deduct tax from payments made to subcontractors and pass those deductions to HMRC.

Contractor – A business or individual that pays subcontractors for construction work, and is responsible for making and reporting CIS deductions.

Subcontractor – A self-employed individual, partnership, or limited company that carries out construction work for a contractor under CIS.

CIS Deduction – The amount withheld from a subcontractor's payment by a contractor and paid to HMRC as an advance against the subcontractor's tax liability.

Gross Payment Status – An HMRC-approved status allowing subcontractors to receive payments in full, with no CIS deductions made at source. Subcontractors must meet compliance and turnover tests to qualify.

CIS Deduction Statement – A document provided by a contractor to a subcontractor showing the gross payment, the amount deducted, and the net payment made. Essential for filing a refund claim.

UTR (Unique Taxpayer Reference) – A ten-digit number issued by HMRC to identify you for tax purposes. Required for CIS registration and Self Assessment filing.

Self Assessment – The annual tax return process used by sole traders and partners to declare income, claim expenses, and reconcile CIS deductions against their actual tax liability.

CIS40 – An HMRC form used by self-employed individuals to claim repayment of CIS deductions during the current tax year, typically used when construction work has ceased before the year end.

CIS41 – An HMRC form used to claim a partner's repayment of CIS deductions within the current tax year.

EPS (Employer Payment Summary) – A submission made by limited companies to HMRC via payroll software, used to offset CIS deductions suffered against monthly PAYE and National Insurance liabilities.

Taxable Profit – Your income after allowable business expenses have been deducted. This is the figure on which your actual tax liability is calculated, not your gross CIS income.

Allowable Expenses – Legitimate business costs that can be deducted from your income to reduce your taxable profit, such as tools, materials, vehicle costs, insurance, and accountancy fees.

Tax Liability – The actual amount of Income Tax and National Insurance you owe for the tax year, calculated after expenses and allowances are applied.

CIS Refund – The repayment made by HMRC when the CIS deductions you have suffered exceed your actual tax liability for the year.

Tax Year – The UK tax year runs from 6 April in one year to 5 April the following year.

HMRC (His Majesty's Revenue and Customs) – The UK government body responsible for collecting taxes and administering schemes including CIS, Self Assessment, and PAYE.

PAYE (Pay As You Earn) – The system used to collect Income Tax and National Insurance from employees. Separate from CIS, which applies to self-employed subcontractors.

R38 – An HMRC form used to claim a tax refund in certain circumstances, including where a worker has been incorrectly treated as a CIS subcontractor rather than an employee.

Compliance Check – An HMRC review of your tax return or claim, triggered when figures appear inconsistent or do not match records held by HMRC, such as contractor CIS submissions.

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