Starting 6 April 2026, CIS fraud rules for contractors in the UK will make them responsible for spotting fraud in their supply chains. HMRC’s new powers mean that businesses that fail to perform proper checks on subcontractors may lose tax privileges, be assessed for unpaid taxes, and face personal penalties. This article explains the changes and outlines practical steps for UK construction firms.
In the Autumn 2025 Budget, the government announced legislation amending Part 3, Chapter 3 of the Finance Act 2004, and the Income Tax (Construction Industry Scheme) Regulations 2005. Starting in April 2026, HMRC can take action against a business that was aware or should have been aware of a payment’s connection to fraudulent tax evasion. Three consequences follow:
The reforms mirror the VAT Kittel test, where businesses can lose tax deductions if they knew or should have known about fraud.
The reforms significantly increase accountability within the Construction Industry Scheme, strengthening CIS compliance for construction contractors in the UK. HMRC’s position is clear: responsibility for identifying fraud no longer sits only with the fraudulent party. It applies to any business that knew or should have known of the fraud risk.
Under the updated rules, HMRC can:
These powers apply to businesses that have engaged in transactions linked to fraudulent tax evasion, even indirectly. HMRC’s guidance confirms that the measures target businesses that knowingly participate in or fail to challenge suspicious arrangements within their supply chain.
Importantly, the scope extends beyond deliberate wrongdoing. The inclusion of the phrase “should have known” places a clear expectation on businesses to carry out appropriate due diligence before entering into transactions.
The measures are designed to target a minority of non-compliant businesses, rather than the wider sector. HMRC explicitly states that compliant businesses conducting proper checks should not face any repercussions.
However, the practical implication is broader. Contractors operating within CIS must now demonstrate that they took reasonable steps to:
If you don’t, you may be liable for fraud, even if your business didn’t profit from it.
These changes reflect a wider policy objective: reducing tax losses, disrupting organised fraud within construction supply chains, and maintaining fair competition across the sector.
The consequences under the revised CIS rules are direct and enforceable under UK tax legislation.
HMRC can take action if it determines that a business knew or should have known about a payment’s connection to fraudulent tax evasion.
HMRC’s internal CIS reform guidance confirms that liability can arise even where the business has met its tax obligations if it entered into a transaction connected to fraud.
Therefore, the financial exposure can encompass the following, especially when construction businesses in the UK fail to manage the CIS fraud risk effectively:
Beyond the immediate tax impact, HMRC expects businesses to demonstrate that they have taken reasonable steps to prevent involvement in fraudulent arrangements. Failure to do so increases the risk of being treated as having participated in non-compliance within the supply chain.
HMRC guidance remains consistent: CIS compliance for construction contractors in the UK requires businesses to conduct appropriate and documented due diligence to avoid these measures. The emphasis lies on the actions taken to ensure their reasonableness.
A defensible approach should include:
The key point is not perfection, but demonstrable, reasonable action. HMRC’s test is based on what a competent business in the same position would have done, given the information available at the time.
The updated CIS rules place clear responsibility on contractors to identify and address CIS fraud risk for construction businesses in the UK. Apex Accountants & Tax Advisors provides practical, focused support to help you meet these expectations with confidence.
We can:
Contact Apex Accountants today for tailored support.
When do the new CIS measures start?
They apply starting April 6, 2026.
What triggers loss of gross payment status?
HMRC can cancel GPS if it proves that a business knew or should have known that a payment was connected to fraud.
How long is the reapplication ban?
If GPS is revoked under the new rules, the business cannot reapply for five years.
What penalties apply?
The HMRC may assess the lost tax and charge a penalty of up to 30 %, which can apply to directors.
What due diligence does HMRC expect?
Verify CIS registrations, check market rates, investigate red flags, and keep detailed records.
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