The UK Home Office has launched the most aggressive illegal working enforcement programme in a generation and London construction is now firmly inside its operational target zone. What began as a hospitality-sector crackdown has evolved into a multi-agency campaign focused on high-risk industries with complex labour supply chains. Construction now sits alongside logistics, facilities management and infrastructure as a priority enforcement sector.
In the first half of 2025 alone, 117 London businesses were fined more than £6.7 million for employing illegal workers, a sharp rise from the £4.6 million issued in the second half of 2024. This acceleration coincides with a national surge in enforcement activity. Home Office transparency data shows that illegal working visits increased by around 40 per cent and arrests by over 40 per cent between mid-2024 and early-2025. By January 2026, enforcement visits and arrests were running nearly 80 per cent higher than pre-election levels.
While hospitality dominates the publicly reported sector breakdown, construction is explicitly identified by the Home Office and sector regulators as a high-risk industry. Immigration raids on construction premises reached record levels in 2025 and are now being deployed as part of intelligence-led, multi-agency operations involving Immigration Enforcement, HMRC, the Gangmasters and Labour Abuse Authority and, increasingly, the Health and Safety Executive.
This is no longer a reactive regime driven by tip-offs and small-scale cash-in-hand trades. It is a data-driven enforcement programme targeting multi-tier supply chains on major sites.
Enforcement cases and financial exposure
Recent enforcement action demonstrates how quickly liabilities can escalate under the post-2024 civil penalty regime.
Sam Construct Ltd, a London-based contractor, was fined £200,000 for illegal workers discovered on an unnamed construction site and a further £180,000 following a separate incident. The company entered liquidation shortly after enforcement action concluded, illustrating how rapidly penalties can destabilise small and mid-sized contractors.
Shengcai Ltd, based in Stratford, was issued a £180,000 civil penalty following a targeted raid. R&F Reinforcement and Construction was fined £120,000 for two illegal workers discovered on a site managed by John Sisk, prompting Sisk to terminate the subcontractor’s engagement across all projects. Vidi Construction’s sites saw multiple subcontractors fined, including West One Construction Ltd at £90,000 and Daniel Tzipi Ltd at £40,000. Even Tier 1 providers have not been immune. Sodexo, a major facilities management contractor with government contracts, was fined £55,000 after onboarding failures at a Camden site.
Sources reports that nine construction firms were fined a combined £950,000 between April and June 2025 alone, while Q1 2025 saw six contractors fined more than £415,000. These figures reflect the impact of the February 2024 penalty uplift, which tripled maximum fines to £45,000 per illegal worker for first offences and £60,000 for repeat breaches.
A single raid identifying ten illegal workers can now generate penalties of £450,000 to £600,000. When multiple sites or repeat incidents are involved, liabilities rapidly move into the high six-figure and seven-figure range.
How enforcement is now being targeted
The Home Office has shifted to intelligence-led operations using data from previous penalties, HMRC tax anomalies, CIS patterns, whistleblowing, union intelligence and public reporting. Construction is prioritised because of its reliance on temporary labour, multi-layer subcontracting and agency supply, all of which create enforcement blind spots.
High-risk indicators now include large multi-tier projects, logistics-heavy developments, infrastructure schemes, high-rise residential builds and public-sector or government-linked projects. Regions with high arrest volumes include London, the West Midlands and the South West, with London consistently recording the highest volume of civil penalties.
Enforcement activity increasingly takes the form of coordinated raids. In the first nine months of 2025, Immigration Enforcement carried out 206 visits to construction premises across the UK, resulting in 477 arrests, almost triple the previous year’s total. High-profile operations at major development sites have seen 25 to 30 workers detained in a single intervention, triggering site shutdowns, removal of large sections of the workforce and immediate programme disruption.
These operations are no longer limited to direct employers, supply chains are now fully in scope.
Principal contractor exposure and supply chain liability
Under the civil penalty regime, liability formally sits with the direct employer unless a statutory excuse can be demonstrated through compliant right-to-work checks. In practice, however, Principal Contractors are now routinely drawn into investigations.
If illegal workers are discovered on a live site, enforcement teams will examine who approved the labour supplier, who verified documentation, who authorised site access, who controlled induction and who exercised supervision. If due diligence is weak, enforcement widens. Where there is evidence that illegal labour was knowingly facilitated or ignored, criminal liability can follow.
The Border Security, Asylum and Immigration Act 2025 is testing liability further up the chain, particularly where contractors exercise effective control over labour supplied via agencies, umbrella companies or CIS arrangements. The Home Office’s policy direction is to extend illegal working prohibitions beyond traditional employment relationships to capture labour-only subcontracting, gig models and false self-employment structures commonly used in construction.
This directly impacts Tier 1 contractors, who now face programme disruption, reputational damage, client scrutiny and potential contractual exposure even where civil penalties are issued against subcontractors.
Labour compliance and the building safety regime
The illegal working crackdown is increasingly intersecting with the Building Safety Act regime.
The Building Safety Regulator’s competence framework requires demonstrable organisational capability, controlled site access, verified workforce competence and auditable records. Illegal workers are inherently unable to meet professional competence requirements. Their presence on site raises immediate questions about management control, governance and safety culture.
On higher-risk buildings, evidence of illegal labour now presents a real risk to Gateway approvals. Discovery of workforce non-compliance can trigger regulatory intervention, refusal of Gateway certification and effective freezing of completion or occupation. The policy trajectory is clearly moving toward integration of labour legitimacy into the broader building safety competence framework.
In effect, workforce compliance is becoming a building safety issue.
Programme, insurance and commercial consequences
The operational impact of enforcement extends far beyond civil penalties. Multi-agency raids routinely involve site shutdowns, removal of a portion of the workforce and extended investigations into subcontractors and labour providers. On tightly programmed London projects with liquidated damages exposure, even short-term disruption can have material commercial consequences.
Civil penalties are not insurable and must be borne directly by the employer. Associated costs, including legal fees, business interruption and reputational management, may only be partially recoverable depending on policy wording. Insurers and funders are increasingly demanding evidence of robust labour compliance systems as part of project risk management.
Contractually, clients are beginning to push labour compliance obligations down through NEC and bespoke contracts, with termination rights and indemnities triggered by enforcement action. Principal contractors, in turn, are seeking to recover losses from subcontractors, although this becomes complex where labour is supplied through multiple tiers.
The enforcement trajectory to 2030
Illegal working enforcement is now a central pillar of UK immigration policy. The political direction is unequivocal. Raids, arrests and penalties are expected to continue rising through the second half of the decade.
Construction is repeatedly cited as a sector with high exploitation risk and structural vulnerability. It is therefore highly likely to remain a priority enforcement target through 2030, particularly in London.
The creation of the Fair Work Agency in 2026 will consolidate labour enforcement powers and strengthen coordination between Immigration Enforcement, HMRC, GLAA and HSE. Data-driven targeting will intensify, using tax records, CIS patterns, procurement data and historical penalty profiles to select sites for intervention.
Gateway and BSR-regulated projects are expected to face enhanced scrutiny, with labour compliance increasingly treated as part of overall dutyholder competence and governance. High-profile schemes will present particularly attractive enforcement targets due to their political and reputational visibility.
Digital workforce control is rapidly becoming the industry response. Biometric access systems integrated with right-to-work verification, CSCS validation and digital induction records are already being deployed on major schemes. By the end of the decade, biometric access and real-time workforce dashboards are likely to be standard on medium-to-large London projects, particularly those regulated by the BSR or delivered for public-sector clients.
The compliance reality for London construction
The enforcement environment has fundamentally changed. Illegal working is no longer treated as a marginal compliance issue. It is now a core regulatory risk with financial, operational, contractual and reputational consequences.
For London construction professionals, labour compliance has become a board-level governance issue. Right-to-work checks, supply chain due diligence, digital access control, audit trails and enforcement response planning are no longer optional administrative processes. They are now central to project delivery, regulatory approval and corporate survival.
The message from government is unambiguous. The crackdown is permanent, the penalties are punitive, and construction is firmly in scope.
This is the new operating environment.
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Expert Verification & Authorship: Mihai Chelmus
Founder, London Construction Magazine | Construction Testing & Investigation Specialist |
