HMRC compliance for construction firms: A complete guide

HMRC compliance for construction firms: What it covers and how to get it right in 2026

Construction businesses face a more complex set of tax and employment obligations than almost any other sector. The Construction Industry Scheme, employment status rules, supply chain due diligence, Right to Work checks, and IR35 all sit alongside standard PAYE and payroll requirements. Getting each one right, consistently, is a significant operational undertaking.

HMRC has increased its focus on the construction sector considerably in recent years, backed by substantial investment in new technology and additional compliance resource. The firms being caught out are not, in the main, trying to cut corners. They are well-run businesses that have gaps in their compliance processes, often without realising it.

The good news is that HMRC compliance is entirely manageable. With the right systems, the right documentation, and the right support in place, construction firms of any size can meet their obligations with confidence and get on with running their business.

This guide sets out what HMRC compliance means in practice for construction firms, where the most common risks sit, and what a robust compliance framework looks like.

What HMRC compliance means for construction firms

HMRC compliance in construction is not a single obligation. It is a collection of interconnected responsibilities, each with its own rules, reporting requirements, and consequences if handled incorrectly. Understanding the full picture is the starting point for managing it well.

The Construction Industry Scheme (CIS)

CIS is the framework that governs how contractors pay subcontractors in the construction sector. Contractors are responsible for verifying each subcontractor’s tax status with HMRC, applying the correct deduction rate (gross, 20%, or 30%), submitting accurate monthly returns, and providing deduction statements to subcontractors.

The scheme sounds straightforward in principle. In practice, the rules around what qualifies as a gross payment for labour versus materials, which subcontractors fall within scope, and how to handle subcontractors who operate as labour providers are genuinely complex. Errors in any of these areas can result in the contractor being held liable for underpaid tax, not the subcontractor.

Employment Status

Correctly determining whether a worker is employed or self-employed is one of the most consequential decisions a construction firm makes. Get it wrong, and HMRC can reclassify workers as employees and issue a determination covering unpaid income tax and National Insurance, potentially stretching back several years.

The key point here is that employment status is determined by the actual working arrangements, not by what a contract says. A contract that describes a worker as self-employed will not protect a contractor if the day-to-day reality of the engagement looks like employment. HMRC inspectors look at the substance of the relationship, including control, substitution rights, and financial risk.

IR35 and off-payroll working

IR35 rules apply where a contractor engages workers through their own limited companies. In the construction sector, this most commonly affects consultants, project managers, and specialist technical roles. Where IR35 applies, the engaging business is responsible for determining employment status and, in many cases, for deducting the appropriate tax at source.

Right to Work

Construction firms are legally required to check that every worker has the right to work in the UK before they begin. Failure to carry out correct checks, or to maintain proper records of those checks, can result in civil penalties of up to £60,000 per illegal worker. The checks must be carried out in the prescribed way; an informal check that does not follow the correct process does not provide a statutory excuse.

A summary of key obligations

Obligation	Who it applies to	Key risk if missed
CIS registration and monthly returns	All contractors	Tax liability, penalties
Subcontractor verification	All contractors	Incorrect deduction rate, liability for underpayment
Employment status assessment	All firms engaging self-employed workers	Worker reclassification, back-tax liability
IR35 determination	Firms engaging limited company workers	Tax and NI liability
Right to Work checks	All employers	Civil penalties up to £60,000 per worker
Supply chain due diligence	Contractors with subcontracted supply chains	Liability for connected fraud or non-compliance

 

Why construction firms are under more scrutiny now

HMRC’s compliance activity in the construction sector has stepped up considerably. The government has invested £1.7 billion in new technology and additional compliance staff, with the explicit aim of closing the tax gap. In the first half of the 2025-26 tax year alone, HMRC secured more than £15 billion through compliance activities across all sectors, with construction among its primary targets.

The practical effect of this investment is that HMRC’s systems are now significantly better at identifying discrepancies. Cross-referencing payments across supply chains, flagging mismatches between CIS returns and subcontractor records, and identifying patterns that suggest incorrect employment status assessments are all increasingly automated. What might previously have gone unnoticed now triggers a review.

This does not mean the system is out to catch honest businesses. It means the margin for administrative error has narrowed, and that firms which have been applying the rules imperfectly, even in good faith, are more likely to find themselves subject to a compliance check.

From 6 April 2026, HMRC’s new powers under the Finance Bill 2025-26 also give it the ability to immediately remove Gross Payment Status where a business is found to have knowingly, or should have known it was, participating in a fraudulent transaction. The reapplication bar rises from one year to five, and penalties of up to 30% of the lost tax can be applied to the business and its directors personally.

What triggers a compliance check

HMRC uses a range of methods to identify firms for review. Common triggers include:

• Discrepancies between CIS monthly returns and subcontractor records held by HMRC
• Inconsistencies in how labour and materials costs are split in payments to subcontractors
• Employment status indicators that do not match the self-employed classification being applied
• Supply chain connections to businesses with known compliance issues
• Anomalies in company accounts, such as expenses that do not match the firm’s operating profile
  
  

It is also worth noting that HMRC inspectors now routinely review publicly available information, including company websites and LinkedIn profiles, as part of their evidence-gathering. A firm’s public-facing description of how it operates can, in some cases, raise questions about how it classifies its workforce.

The message for construction businesses is straightforward: the compliance environment has changed, and the processes that may have been adequate five years ago may not be sufficient today. The answer is not to worry, but to review.

What good HMRC compliance looks like in practice

Compliance is not about having the most complex systems. It is about having the right processes, applied consistently, with clear documentation to support them. For most construction firms, that means addressing five core areas.

1. Accurate and timely CIS reporting

Monthly CIS returns must be submitted on time and must accurately reflect every subcontractor payment made in that period. This includes correctly splitting labour and materials costs, applying the right deduction rate for each subcontractor, and reporting in the correct fields. HMRC’s systems now cross-reference returns against other data it holds, so returns that are internally consistent but do not match wider records will attract attention.

Subcontractor verification should be completed before the first payment is made, and the outcome of that verification should be documented and retained.

2. Robust employment status assessment

Every engagement with a self-employed worker should be supported by a genuine assessment of their employment status, based on the actual terms and working arrangements. That assessment should be documented. Contracts must reflect the reality of the engagement; a contract that says one thing while the working relationship looks quite different will not withstand scrutiny.

This applies equally to workers engaged through their own limited companies, where IR35 considerations need to be worked through carefully before the engagement begins.

3. Watertight contracts

Contracts are the documentary foundation of any employment status or CIS compliance position. They need to be specific, accurate, and reflective of how the engagement actually works. Poorly drafted contracts, or contracts that do not match the operational reality, are one of the most common reasons otherwise compliant firms find themselves in difficulty during an HMRC review.

“This case serves as a warning that poorly-drafted contracts are as bad as no contracts at all.” – Dan Davies, Compliance Director, Hudson Contract

4. Supply Chain Due Diligence

Contractors are responsible for the compliance of their supply chains. From April 2026, that responsibility is more explicit: where HMRC can show that a business knew, or should have known, that a transaction was connected to fraud, it can hold that business liable for the lost tax. This raises the bar for supply chain checks significantly.

Good due diligence means verifying the status of subcontractors before engaging them, monitoring for changes, and maintaining records that demonstrate the checks were carried out properly.

5. Right to Work Checks

Every worker must be checked before they start. The check must follow the prescribed process set out by the Home Office, and records must be retained. A statutory excuse against a civil penalty is only available where the check was carried out correctly and in full.

For firms with large or frequently changing workforces, this is an area where gaps in process can accumulate quickly.

If HMRC contacts you

Receiving a letter from HMRC is not, in itself, a cause for alarm. HMRC uses a range of contact methods, from informal “nudge” letters prompting firms to review specific areas, through to formal compliance checks and full investigations. Each requires a different response.

Nudge letters and one-to-many campaigns

HMRC has been sending nudge letters to large groups of construction contractors as part of its “one-to-many” compliance campaigns. These are not formal compliance checks. They are prompts to review a specific aspect of your returns or processes. Firms typically have 45 days to respond; if no action is taken, HMRC can escalate to a formal check.

The right response to a nudge letter is to take it seriously, review the area it refers to, and respond in a timely and considered way. A well-documented review, demonstrating that you have looked at the issue and are satisfied with your position, is a perfectly reasonable response.

Formal compliance checks

A formal compliance check is a more structured process. HMRC will typically request specific records and documentation, and may ask detailed questions about your CIS processes, employment arrangements, or supply chain. Inspections are now frequently conducted entirely by correspondence, with no face-to-face contact.

The quality of your documentation at this point is critical. Firms that can produce clear, accurate records of their CIS returns, employment status assessments, contracts, and Right to Work checks are in a far stronger position than those who cannot.

The value of professional representation

Having specialist support during a compliance check makes a material difference to the outcome. An experienced compliance adviser knows what HMRC is looking for, how to respond to requests for information, and how to present your position clearly and accurately. They can also identify and address any genuine gaps before they become the focus of the investigation.

Hudson Contract has been representing construction firms in HMRC compliance checks for nearly 30 years and has a 100% success rate in employment status cases. That track record is built on thorough preparation, accurate documentation, and a deep understanding of how HMRC approaches construction sector reviews.

How Hudson Contract supports construction firms with HMRC compliance

Hudson Contract works with more than 2,600 construction businesses across the UK, handling 1.8 million subcontractor payments every year. HMRC compliance is not a bolt-on service; it is the core of what we do.

For firms that want complete confidence in their compliance position, Hudson provides:

• CIS management: Subcontractor verification, accurate deduction calculations, monthly return submission, and proactive checks to identify issues before they reach HMRC.
• Employment status protection: Assessment of every subcontractor engagement, with documented status determinations and a guarantee backed by nearly 30 years of case history.
• Contract review and drafting: Ensuring that contracts accurately reflect the working arrangements they describe and will withstand scrutiny if reviewed by HMRC.
• Supply chain due diligence: Checks on the businesses in your supply chain to protect your position under the April 2026 “knew or should have known” standard.
• Right to Work checks: Carrying out prescribed checks on your behalf and indemnifying you against Home Office penalties.
• Mock CIS inspections: A proactive review of your CIS processes and records, identifying any gaps or inconsistencies before HMRC does.
• HMRC representation: If HMRC does open a compliance check, Hudson takes on the process on your behalf, managing all correspondence and presenting your case.
  
  

The result is not just that your compliance obligations are met. It is that you have a complete indemnity against the consequences of any issues that arise, and the confidence to focus on running your business rather than managing your tax position.

For construction firms that want to understand more about how HMRC compliance works in their specific circumstances, or that want a review of their current position, Hudson’s team is available for a no-obligation conversation. There are no complex onboarding requirements and no pressure. Just straightforward, specialist advice from people who have been working in this sector for decades.

To find out more about how Hudson can support your business, read our recent coverage of HMRC’s increased focus on CIS errors and the rise in compliance checks for CIS contractors, or speak to our team today.