Very few areas of UK tax cause as much day to day confusion for construction businesses as the Construction Industry Scheme. Subcontractors regularly find money deducted from their invoices before they have even seen it, and many do not fully understand why the amount varies from one contractor to another, or how to get some of it back. Since April 2026, HMRC has also tightened compliance expectations across the scheme, with stricter verification requirements and higher penalties for contractors who get it wrong.
Disclaimer: This article is for general information only and reflects HMRC guidance confirmed for the 2026/27 tax year at the time of writing. Construction Industry Scheme obligations depend on the specific structure and history of each business. Always seek specific advice tailored to your own circumstances.
This article explains how CIS deductions actually work, how verification and gross payment status operate, what happens if returns are filed late, and how subcontractors reclaim tax they have overpaid during the year.
What the Construction Industry Scheme Actually Does
The Construction Industry Scheme requires contractors to deduct money from payments made to subcontractors for construction work and pay it directly to HMRC, as an advance payment towards the subcontractor's own tax and National Insurance. A contractor for these purposes is not limited to businesses that would obviously describe themselves that way. It includes any business that pays subcontractors for construction work, and it also captures businesses outside the construction industry itself that spend more than £3 million on construction in the twelve months since their first payment, sometimes called deemed contractors.
Subcontractors are not legally required to register for CIS, but there is very little reason not to, since the deduction rate applied to unregistered subcontractors is deliberately set much higher than the rate applied to those who are registered.
The Three Deduction Rates
There are three possible CIS deduction rates, and the rate that applies to a particular subcontractor is determined by HMRC during the verification process, not chosen by the contractor making the payment.
A rate of 30% applies to subcontractors who are not registered for CIS, or whose details cannot be matched by HMRC during verification. A rate of 20% applies to subcontractors who are registered for CIS in the normal way. A rate of 0% applies to subcontractors who have successfully applied for and hold gross payment status, meaning no deduction is made at all and the subcontractor is responsible for settling their own tax and National Insurance through the normal Self Assessment or Corporation Tax process.
Crucially, the deduction only applies to the labour element of a payment. Genuine materials costs, meaning the direct cost the subcontractor can demonstrate they paid for materials specifically relating to that contract, are excluded from the calculation entirely. This is one of the most common points of confusion, and getting the invoice breakdown wrong can needlessly expose the full payment, materials included, to deduction.
Worked Example 1: Calculating a Standard 20% Deduction
Halbury Groundworks Ltd invoices a main contractor £8,000 for a job, made up of £5,500 for labour and £2,500 for materials it purchased directly and can evidence with supplier receipts. Halbury is registered for CIS but does not hold gross payment status, so the standard 20% rate applies.
The deduction is calculated only on the labour element. £5,500 multiplied by 20% comes to £1,100. The contractor pays Halbury £6,900, being the full £8,000 invoice less the £1,100 deduction, and sends the £1,100 to HMRC on Halbury's behalf. Had Halbury failed to separate out the materials cost on its invoice, the full £8,000 could have been treated as subject to deduction, costing an extra £500 in cash flow that would only be recovered later.
Verifying a Subcontractor Before the First Payment
Before making a first payment to a new subcontractor, a contractor must verify them with HMRC, either through commercial payroll software or HMRC's own online service, to confirm whether they are registered and at what rate deductions should be made. HMRC responds with a verification reference and confirms the applicable rate.
Once a subcontractor has been verified and paid, the contractor generally does not need to verify them again provided they have paid that same subcontractor at some point within the current tax year or either of the two previous tax years. A gap longer than that requires the subcontractor to be verified again before further payments are made.
Gross Payment Status and Why It Matters
For an established, growing subcontractor, gross payment status can make a significant difference to cash flow, since it means being paid the full invoice value with no deduction at all, settling the tax due through the normal Self Assessment or Corporation Tax process instead. To qualify, a subcontractor must pass three separate tests.
The business test requires evidence of a genuine UK construction business, run mainly through a business bank account. The turnover test requires annual construction turnover, excluding VAT and materials, of at least £30,000 for a sole trader, or £30,000 multiplied by the number of relevant people for a partnership or limited company, subject to an overall cap. The compliance test looks at the subcontractor's recent record of filing returns and paying tax on time, and a pattern of late filing in the period before an application is one of the most common reasons an application is refused.
Gross payment status is not granted permanently. HMRC reviews it, and a poor compliance record after it has been granted, such as late CIS returns or late tax payments, can lead to it being withdrawn, after which reapplication is generally not possible for twelve months.
Worked Example 2: The Cash Flow Difference of Gross Payment Status
Renton Electrical Ltd invoices £15,000 for labour on a single job. Without gross payment status, at the standard 20% rate, £3,000 is deducted and sent to HMRC before Renton sees any of it, leaving £12,000 received against the labour element of that invoice. With gross payment status, Renton receives the full £15,000 immediately, and settles its actual tax liability through its Corporation Tax return once its real profit for the year is known, rather than having tax deducted up front on turnover regardless of profit.
Across a busy year with a large number of invoices, this difference compounds substantially, which is why growing subcontractors with a clean compliance record generally find it worth applying.
Filing Returns and the Cost of Getting It Wrong
Contractors must submit a monthly return to HMRC, form CIS300, by the 19th of the month following each CIS tax month, which runs from the 6th of one calendar month to the 5th of the next. This applies even in months where no subcontractors were paid, in which case a nil return is still required unless HMRC has been formally notified that no return is expected for a period.
Deductions themselves must be paid over to HMRC by the 19th of the following month if paying by post, or the 22nd if paying electronically.
Late filing penalties are automatic and escalate quickly. A return that is even one day late attracts a fixed penalty of £100. If it remains outstanding two months after the deadline, a further £200 penalty is added. At six months late, a further penalty applies, the greater of £300 or 5% of the CIS deductions shown on the return. At twelve months late, a further penalty on the same basis applies again, and where HMRC considers the failure to have been deliberate, penalties beyond twelve months can rise as high as £3,000 or 100% of the deductions involved.
Since April 2026, HMRC has also tightened its expectations around ongoing compliance more broadly, requiring contractors to be able to demonstrate proper verification of subcontractors and continued monitoring of engagements throughout the year, with increased responsibility placed on contractors for fraud occurring elsewhere in their supply chain. This makes keeping clean, contemporaneous verification and payment records more important than it has ever been.
Worked Example 3: How Quickly CIS Penalties Add Up
A contractor with returns due for both March and April accidentally misses both deadlines and does not file until six months later. Each missed return attracts its own penalty stack independently, so the £100 initial penalty, the £200 two month penalty, and the six month penalty of the greater of £300 or 5% of that month's deductions all apply separately to each of the two late returns. A relatively short administrative lapse covering only two months of returns can therefore easily result in penalties well over £1,000 once both are added together.
Reclaiming Overpaid CIS Deductions
Because CIS deductions are taken from turnover rather than profit, most subcontractors end up having more tax deducted during the year than they actually owe once their real business expenses are taken into account. Reclaiming this overpayment works differently depending on how the subcontractor is structured.
Sole traders and partnerships reclaim through their Self Assessment tax return. The CIS deductions suffered during the year are entered on the return, HMRC calculates the actual tax due based on real profit, and any excess is refunded in the normal way, in the same manner as any other Self Assessment repayment.
Limited companies reclaim differently, since a company does not complete a personal Self Assessment return. CIS deductions suffered are first offset against the company's own PAYE and National Insurance liabilities as an employer. Any deductions left over after that can be carried forward and offset against the company's Corporation Tax liability. If there is still a surplus after both of those offsets, a separate repayment claim must be made directly to HMRC, since it is not issued automatically. A subcontractor company with limited PAYE liability of its own and a modest Corporation Tax bill can end up waiting until well after its year end accounts are finalised before recovering a significant CIS overpayment, which is a real cash flow consideration worth planning around.
Frequently Asked Questions
Do I have to register for CIS if I am a subcontractor?
No, registration is not compulsory, but an unregistered subcontractor is deducted from at 30% rather than the 20% standard rate, so registering is almost always worthwhile unless there is a specific reason not to.
What counts as materials for the purposes of excluding them from the deduction?
Materials must be the direct cost the subcontractor themselves paid for items specifically used in that contract, evidenced by supplier invoices or receipts. Costs such as plant hire that is separately invoiced, and fees for professional services like architecture or surveying, are also generally excluded from CIS deductions entirely, but the position depends on exactly how the invoice is structured.
How long does it take to get gross payment status once I apply?
There is no fixed statutory timescale, though HMRC typically aims to process applications within a few weeks provided the three qualifying tests are clearly met and the application is complete. Having clean, up to date tax filing and payment history before applying significantly improves the chances of a smooth approval.
Can gross payment status be taken away once granted?
Yes. HMRC reviews compliance on an ongoing basis, and a poor record after status has been granted, particularly late CIS returns or late tax payments, can lead to it being withdrawn. Once withdrawn, a further application generally cannot be made for twelve months.
What happens if HMRC cannot match my details during verification?
If your details as a subcontractor cannot be matched to HMRC's records, most commonly due to using a different name or Unique Taxpayer Reference than the one HMRC holds, you will be treated as unregistered and deducted from at 30% until this is corrected. Double checking that the details supplied match exactly what is registered with HMRC before a first payment is a simple way to avoid this.
Do CIS deductions apply to VAT?
No. CIS deductions are calculated on the payment excluding VAT. Separately, most construction services between VAT registered businesses within the scheme are subject to the domestic reverse charge for VAT, which changes how VAT itself is accounted for on the invoice, but this operates independently of the CIS deduction calculation.
As a limited company subcontractor, can I get my CIS refund faster?
The offset against PAYE and Corporation Tax happens automatically as those liabilities fall due, so the practical speed of recovering an overpayment depends largely on how much PAYE and Corporation Tax the company has to offset it against during the year. Keeping accurate, up to date management accounts makes it easier to identify a build up of recoverable CIS early, and to submit a repayment claim for any remaining surplus as soon as it is due, rather than waiting until the year end accounts are finalised.
What CoreAcc Accountants Can Help You With
CIS is one of the areas where good record keeping directly protects your cash flow, not just your compliance position. CoreAcc Accountants helps construction sector clients verify subcontractors correctly, structure invoices so materials are properly excluded from deductions, apply for gross payment status where it makes sense, file monthly returns on time, and reclaim overpaid CIS tax as efficiently as possible, whether you operate as a sole trader, partnership or limited company.
Get in Touch
If CIS deductions are tying up more of your cash than they should, or you are not confident your current record keeping would stand up to HMRC's tightened compliance expectations, contact CoreAcc Accountants and we will review your position.
CoreAcc Accountants is an ACCA accredited firm of Chartered Certified Accountants based in Borehamwood, Hertfordshire. This article was published in September 2026 and reflects HMRC guidance confirmed for the 2026/27 tax year at the time of writing. It does not constitute professional or legal advice. Always seek specific advice tailored to your individual circumstances.
