Key takeaways

• CIS deducts 20% from the labour portion of your invoices:
  That money is a credit against your corporation tax, not a final payment
• You cannot claim a CIS material deduction for equipment you own:
  HMRC specifically targets this error in scaffolding compliance visits
• The timing mismatch creates a significant cash flow drag:
  You overpay HMRC throughout the year and recover at year-end
• You can offset CIS deductions against monthly PAYE:
  If you have employees, this speeds up recovery significantly
• Gross payment status removes the deduction entirely:
  Apply when your compliance record and turnover qualifies you

The Construction Industry Scheme (CIS) is one of those topics that every scaffolding director knows exists but not everyone fully understands, until HMRC brings it to their attention. CIS affects how you are paid by main contractors, what gets deducted from your invoices, and what you can legitimately claim back. Getting it wrong can cost money, attract HMRC compliance visits, and create cash flow problems that compound over time.

This guide explains how CIS works for scaffolding limited companies, the significant cash flow implications of the deduction mechanism, and a specific and costly compliance error that HMRC targets in scaffolding sector visits.

What is the Construction Industry Scheme?

Quick answer
The Construction Industry Scheme (CIS) requires contractors to deduct tax from payments to subcontractors before paying them, then pass those deductions to HMRC. Deductions are advance payments against the subcontractor’s tax liability, credited against corporation tax at year-end. If your scaffolding company works for main contractors or is paid by other contractors, you are almost certainly within CIS.

Are you within CIS?
You are a CIS subcontractor if a main contractor deducts tax before paying your limited company. You are a CIS contractor if your company pays subcontractors for construction work. Many scaffolding companies operate in both roles simultaneously, acting as a subcontractor to the main contractor and as a contractor to their own labourers or sub-contractors.

CIS applies to most construction operations, including scaffolding erection and dismantling. Some activities are specifically excluded, such as scaffolding hire without labour. If you are uncertain whether a specific type of work is within CIS, the most reliable approach is to check with your accountant or refer to HMRC’s published CIS guidance.

CIS deduction rates

When a contractor pays a CIS subcontractor, they must first verify the subcontractor’s status with HMRC. Based on that status, tax is deducted at one of three rates before payment is made:

• Gross payment status, 0% deduction:
  Available to businesses with a strong compliance record, sufficient turnover and a clean tax history. You receive the full payment and are responsible for paying your own taxes. This is the most cash-flow-friendly position and worth applying for when your business qualifies.
• Net payment status, 20% deduction:
  The standard rate for verified subcontractors. The contractor deducts 20% of the qualifying labour element before making payment. This money goes directly to HMRC on your account.
• Higher rate, 30% deduction:
  Applied to subcontractors who cannot be verified by HMRC, either because they are not registered for CIS or cannot be found on HMRC’s system. If you are receiving 30% deductions, resolving your CIS registration should be an immediate priority.

What CIS deductions are calculated on: and the critical scaffolding error

Quick answer
CIS deductions apply only to the labour element of your invoice, not materials. If your scaffolding company owns its equipment outright, it cannot claim a CIS material deduction for that equipment. Only third-party hire costs, equipment actually hired from another business for the specific job, can be excluded as materials. HMRC specifically targets this error in scaffolding compliance visits.

The rule seems straightforward but is a consistent source of errors in the scaffolding sector. Here is the logic: materials that can be excluded from CIS deductions are costs the subcontractor has genuinely incurred for the work, specifically items purchased or hired from third parties for that job. The idea is that the subcontractor is passing on a cost rather than generating income from those materials.

Scaffolding equipment that your company owns outright does not meet this test. You have not hired or purchased it for the specific job. It is a business asset. Claiming a material deduction for owned equipment reduces the CIS deduction incorrectly, which means the main contractor withholds less tax than it should and passes that shortfall risk back to HMRC.

HMRC compliance focus: scaffolding specific
HMRC compliance visits regularly identify scaffolders claiming material deductions for equipment they own outright. This is one of the most common CIS compliance errors in the scaffolding sector. When HMRC identifies it, the underpayment of CIS becomes a liability of the contractor (the main contractor who made the payment), not the subcontractor. However, it reflects poorly on the subcontractor’s compliance record and can trigger further scrutiny.Only third-party hire costs for equipment hired specifically for the job can be included as materials in the CIS calculation.

HMRC’s published guidance on this specific point is in the CIS 340 guide at gov.uk, under the section on materials and deductions.

The cash flow impact of CIS deductions

You receive less cash per invoice

A 20% CIS deduction means that for every £10,000 of labour invoiced, you receive £8,000. The remaining £2,000 is held by the main contractor and paid to HMRC on your account as an advance against your tax. This is not lost money: it is credited against your corporation tax at year-end. But it is money you do not have access to in the interim.

The timing mismatch

CIS deductions are made when each invoice is paid, continuously throughout the year. The credit against your corporation tax liability only materialises at year-end, when your accounts are prepared and your CT600 is filed. Throughout the trading year, your business is effectively overpaying HMRC on account, and that cash is locked up until the annual reconciliation.

The scale of the drag

For a scaffolding company generating £500,000 in labour revenue per year at standard 20% CIS, the total annual deduction is £100,000. If the company’s actual corporation tax liability is £40,000, it has a £60,000 credit with HMRC at year-end. But throughout the year, that £60,000 is unavailable to the business. Depending on the timing of the year-end and the time to process the return, the business might be waiting 12 to 15 months for that cash.

For growing businesses, this drag compounds year on year: as turnover increases, the CIS deduction increases with it, and the gap between what is deducted and what is owed continues to grow.

How to reclaim CIS overpayments

Through your Company Tax Return

CIS deductions suffered by your limited company are set against your corporation tax liability through the CT600. Your accountant records the total CIS deductions suffered during the year on the return. If deductions exceed the tax owed, HMRC processes a repayment. HMRC aims to process CT600 repayments within 28 days of filing, though this can vary.

By offsetting against monthly PAYE

Quick answer
If your company operates PAYE for employees, you can offset CIS deductions suffered against the PAYE and National Insurance you owe HMRC each month. This is done through the employer payment summary (EPS) submitted to HMRC via payroll software. This recovers the cash throughout the year rather than waiting until year-end, which can make a significant difference to monthly cash flow.

To use this offset, your payroll software must be set up to record CIS deductions suffered and include them on the EPS submission. If CIS deductions for the month exceed the PAYE and NIC due, you can claim the difference back from HMRC as an in-year repayment. This is one of the most effective tools available to scaffolding businesses for improving cash flow within the CIS system.

Gross payment status: the goal for established businesses

Gross payment status (GPS), where the contractor pays you in full without deducting CIS, is the most cash-flow-friendly position available to any scaffolding subcontractor. Instead of receiving 80p in the pound and waiting for the remaining 20p at year-end, you receive 100% of each payment and manage your own tax affairs.

HMRC grants GPS to businesses that meet all of the following criteria: they have been trading and complying with all tax obligations for at least 12 months; their annual turnover from construction work is at or above the relevant threshold (for a company, this is £30,000 per director or £100,000 for the business); and they have a clean compliance record with returns filed on time and taxes paid on time.

Apply for gross payment status through your HMRC online account. Further guidance at gov.uk/what-is-the-construction-industry-scheme.

CIS obligations if your company uses subcontractors

If your scaffolding limited company pays its own subcontractors for construction work, you have contractor obligations under CIS. These must be met regardless of whether your own company is operating under gross payment status or net payment status as a subcontractor to others.

Contractor obligations include: registering as a CIS contractor with HMRC; verifying any new subcontractor’s CIS status before the first payment; deducting CIS at the appropriate rate (0%, 20% or 30%) from qualifying labour payments; paying the deductions to HMRC by the 19th of the following month (or 22nd for electronic payment); and submitting a monthly CIS return to HMRC by the 19th.

Failure to submit monthly CIS returns results in fixed penalties starting at £100 per return, escalating to £200, and further tax-based penalties for returns that are 6 or 12 months late. These penalties apply even if no deductions were made in the period: a nil return must still be submitted if you are registered as a contractor.