What is a CIS tax deduction? | 2026/27 UK Tax Guide

If you operate in the UK construction sector, the Construction Industry Scheme (CIS) dictates how you handle payments. Whether you act as a contractor paying for labour or a subcontractor receiving payment, you must understand the rules. When clients ask, “What is a CIS tax deduction?”, they are asking about the statutory mechanism that forces contractors to withhold a portion of a subcontractor’s pay to cover their future tax liabilities.

For the 2026/27 tax year, the CIS rules interact heavily with the new Making Tax Digital (MTD) mandate and recent Gross Payment Status compliance changes. This guide breaks down exactly how the deductions work, the rates applied, and your statutory obligations.

The Mechanics: What is a CIS tax deduction?

A CIS tax deduction is an advance payment towards a subcontractor’s Income Tax and National Insurance Contributions (NICs). Under section 61 of the Finance Act 2004, the CIS places a statutory obligation on contractors to deduct tax at source from payments made to subcontractors, and to pay that money directly to HMRC.

Crucially, the contractor only applies this deduction to the labour element of the invoice. The deduction explicitly excludes the direct cost of any materials (exclusive of VAT) that the subcontractor purchased to fulfil the contract.  HMRC also applies a concession that allows subcontractors to treat the cost of plant hire as materials for CIS deduction purposes.

CIS Deduction Rates (20%, 30%, and 0%)

Following verification, HMRC informs the contractor what rate to deduct from the subcontractor’s payments.  The contractor applies one of three rates:

1. The Standard Rate (20%): If the subcontractor registers for CIS and HMRC successfully verifies them, the contractor deducts 20% from the labour element of their payments.
2. The Higher Rate (30%): If the subcontractor fails to register for CIS, or HMRC cannot match their details during the verification process, the contractor must apply a penal 30% deduction rate.
3. Gross Payment Status (0%): If the subcontractor meets specific stringent requirements and successfully applies for Gross Payment Status (GPS), the contractor pays them 100% of their invoice with a 0% deduction.

The CIS provides for payments by contractors to subcontractors in the construction industry to be subject to deduction of amounts on account of the subcontractor’s tax. The CIS tax was introduced to address concerns about widespread tax evasion in the construction industry.”

Gross Payment Status (GPS) and VAT Compliance

Securing Gross Payment Status dramatically improves a subcontractor’s cash flow, making them a more attractive party for contractors to deal with.  To obtain GPS, a subcontractor must pass three statutory tests: the Turnover Test, the Business Test, and the Compliance Test.

The 2024/25 VAT Rule Update

HMRC actively monitors compliance to maintain a subcontractor’s GPS. From 6 April 2024, the government strengthened the GPS compliance test to explicitly include VAT compliance.  HMRC now has the power to immediately cancel a subcontractor’s Gross Payment Status if they fail to meet their VAT obligations, forcing them back onto the standard 20% deduction rate.

Contractor Obligations: Verification and Returns

The administrative burden of the CIS falls entirely on the contractor.

Verification

Under regulation 6 of the Income Tax (Construction Industry Scheme) Regulations 2005 (SI 2005/2045), a contractor must verify a subcontractor with HMRC before making a contract payment.  The contractor does not need to re-verify a subcontractor if they have included that subcontractor on a CIS return in the current or previous two tax years.

Returns and Payments

The contractor must file monthly CIS returns (CIS300) detailing the payments made and the tax deducted.  Furthermore, regulation 7 dictates that the contractor must pay the deducted amounts to HMRC within 17 days after the end of the tax period if using an approved electronic payment method, or within 14 days otherwise.

To provide the subcontractor with proof of the deduction, contractors issue Payment and Deduction Statements (PDS). The subcontractor then uses these statements to offset the CIS deductions against their final Self Assessment tax bill (or Corporation Tax and PAYE bills if operating as a limited company).

The 2026/27 Landscape: Making Tax Digital (MTD)

The 2026/27 tax year brings a massive compliance shift for self-employed subcontractors. From 6 April 2026, the government mandates Making Tax Digital for Income Tax for sole traders whose qualifying income exceeds £50,000.

If a sole trader subcontractor breaches this £50,000 threshold, they can no longer wait until January to declare their income and claim back their CIS deductions on a single annual tax return. Instead, they must use MTD-compatible software to create, store, and correct digital records of their income and expenses, and send quarterly updates directly to HMRC.  Subcontractors must ensure their accounting software accurately captures the gross invoice amount and the CIS deducted to ensure they do not overpay tax.

Summary of CIS Deductions

For completeness, if HMRC discovers that a contractor has failed to deduct the correct amount of CIS tax, or has failed to pay it over, regulation 13 of the CIS Regulations empowers HMRC to issue a determination to recover the shortfall directly from the contractor, shifting the financial liability away from the subcontractor.

Next steps: Audit your subcontractors’ VAT filing history to ensure their Gross Payment Status is not at risk of cancellation, and transition any sole traders earning over £50,000 onto MTD-compatible software before the 6 April 2026 deadline.