What Is the Construction Industry Scheme (CIS)? A Practical Guide for Contractors and Subcontractors
The UK construction sector operates under a specialist tax framework known as the Construction Industry Scheme (CIS). While many contractors and subcontractors understand that CIS involves tax deductions from payments, fewer fully understand how the scheme works, what gross payment status means, and why HMRC is increasing scrutiny of supply chain compliance.
With new anti-fraud measures being introduced by HMRC from April 2026, construction businesses face greater responsibility for verifying the legitimacy of their subcontractors and protecting their CIS compliance position.
For contractors, subcontractors, and property developers alike, understanding CIS is now more important than ever.
What Is CIS?
The Construction Industry Scheme is a tax deduction system operated by HMRC for businesses involved in construction work in the UK. Under the scheme, contractors deduct money from subcontractor payments and pass those deductions to HMRC as advance payments towards tax and National Insurance.
CIS was introduced to reduce tax evasion within the construction industry and ensure tax is collected at source. It applies to a wide range of construction activities, including:
Building and refurbishment work
Demolition and site preparation
Repairs and alterations
Electrical, plumbing, and heating installations
Decorating and finishing work
The scheme generally applies whenever a contractor pays a subcontractor for construction operations.
Who Must Register for CIS?
There are two main parties within CIS:
Contractors
A contractor is a business or individual that pays subcontractors for construction work. Contractors are responsible for:
Registering for CIS with HMRC
Verifying subcontractors
Deducting CIS tax where required
Filing monthly CIS returns
Keeping accurate payment records
Subcontractors
A subcontractor is a business or self-employed worker carrying out construction work for a contractor. Subcontractors can register under CIS to reduce the rate of deductions applied to their payments.
How CIS Deductions Work
The amount deducted under CIS depends on the subcontractor’s registration status.
Not registered with HMRC - 30%
Registered under CIS - 20%
Gross Payment Status - 0%
These deductions apply only to labour elements of invoices and not usually to materials or VAT.
For example, if a subcontractor submits an invoice for £5,000 labour and £1,000 materials, CIS deductions are normally calculated only on the £5,000 labour element.
What Is Gross Payment Status?
Gross Payment Status (GPS) allows subcontractors to receive payments in full without CIS deductions being withheld by contractors.
Rather than paying tax through deductions during the year, subcontractors with GPS are responsible for settling their tax liabilities directly with HMRC through Self Assessment or Corporation Tax.
Gross payment status can significantly improve cash flow, particularly for growing construction businesses. However, obtaining and retaining GPS requires strict compliance with HMRC rules.
How to Qualify for Gross Payment Status
To qualify for GPS, HMRC requires businesses to meet several conditions, including:
A strong tax compliance history
Construction work carried out in the UK
Business operations through a bank account
Minimum turnover thresholds
Current turnover requirements include:
£30,000 for sole traders
£30,000 per partner in a partnership
£30,000 per company director, or £100,000 minimum for the company overall
HMRC also reviews whether tax returns, PAYE obligations, VAT returns, and CIS filings have been submitted and paid on time.
Why HMRC Is Increasing CIS Compliance Checks
HMRC has identified significant fraud risks within construction supply chains, particularly where subcontractors receive gross payments and later fail to pay taxes due.
From April 2026, HMRC will gain stronger powers to tackle CIS fraud. Under the new rules, businesses may face serious consequences if HMRC believes they “knew or should have known” transactions were connected to tax fraud.
Potential consequences include:
Immediate cancellation of gross payment status
Liability for unpaid tax elsewhere in the supply chain
Penalties of up to 30%
Restrictions on reapplying for GPS for five years
The rules mirror the VAT “Kittel principle,” where businesses can become liable if they ignore obvious warning signs of fraud within their supply chains.
Common CIS Red Flags
HMRC increasingly expects contractors to carry out meaningful due diligence before engaging subcontractors.
Examples of potential warning signs include:
Subcontractors charging unusually low rates
Businesses with no trading history
Virtual office addresses
Frequent changes in directors or company structure
Missing CIS deduction statements
Incorrect UTR or verification details
Discussions within contractor and accounting communities also show growing concern around contractors failing to submit CIS returns correctly or deductions not appearing on HMRC systems.
Practical Steps to Stay CIS Compliant
Construction businesses should now adopt a more proactive approach to CIS compliance and subcontractor verification.
Key best practices include:
Verify Every Subcontractor
Always verify subcontractors with HMRC before making payments.
Maintain Proper Records
Keep copies of:
CIS verification numbers
Deduction statements
Contracts and invoices
Due diligence checks
Companies House searches
Monitor Supply Chains
CIS compliance is not a one-time exercise. Businesses should regularly review subcontractor arrangements and identify any emerging risks.
Train Staff
Anyone responsible for onboarding subcontractors should understand CIS rules and recognise fraud indicators.
Seek Professional Advice
Given the increasing complexity of CIS legislation and HMRC enforcement activity, many contractors now work closely with specialist tax advisers or chartered tax accountants to strengthen compliance procedures and reduce risk exposure.
Why CIS Matters for Construction Businesses
For subcontractors, CIS deductions directly affect cash flow and year-end tax liabilities. For contractors, failures in verification or reporting can lead to HMRC penalties and reputational damage.
The latest anti-fraud measures demonstrate that HMRC now expects businesses to actively monitor their supply chains rather than simply process payments.
As HMRC continues to tighten enforcement, robust CIS compliance procedures are becoming an essential part of running a successful construction business.
Final Thoughts
The Construction Industry Scheme remains one of the most important tax regimes affecting the UK construction sector. Whether operating as a contractor or subcontractor, understanding how CIS works is critical for protecting cash flow, maintaining compliance, and avoiding costly HMRC disputes.
With HMRC introducing stronger anti-fraud powers and enhanced scrutiny around gross payment status, construction businesses should review their CIS procedures now rather than waiting for problems to arise.
Working with an experienced Chartered Tax Accountant can help businesses implement effective compliance systems, reduce risk, and navigate the increasingly complex CIS landscape with confidence.
Get in touch:
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