Tackling modern slavery in the construction supply chain

The Modern Slavery Act 2015 mandates that UK commercial organisations with a turnover of £36m or more publish an annual transparency statement. Updated guidance for 2025 shifts the focus from static reporting to “continuous improvement,” requiring businesses to demonstrate year-on-year progress in identifying and remediating forced labour risks within their supply chains. 

In this blog, we cover: 

• Why awareness and compliance with the Modern Slavery Act is important 
• The 2025 updates to the Modern Slavery Act 
• Why eliminating slavery in construction matters 
• How we help main contractors and subcontractors

 

The growing urgency of modern slavery compliance in construction 

A decade on from the introduction of the Modern Slavery Act 2015, the landscape of compliance is shifting significantly. For the UK construction industry, often identified as a high-risk sector due to complex supply chains and reliance on agency labour, the requirement for robust due diligence has never been critical. 

Recent government statistics underscore the severity of the issue: 

• In 2024, 19,125 potential victims of modern slavery were referred to the Home Office 
• This represents a 13% increase from the previous year and the highest number on record 
• Labour exploitation remains the most common form of exploitation for adults, accounting for 41% of adult referrals. 

For main contractors and subcontractors, Modern Slavery Act compliance is no longer a “tick-box” exercise. It is a fundamental governance requirement to mitigate construction supply chain risk and ensure ethical operations.

 

Modern Slavery Act 2025 updates: What has changed? 

While the core legislation of the Modern Slavery Act 2015 remains, the 2025 transparency guidance raises the bar for corporate reporting. The focus has moved from simply having a policy to proving that the policy works.

From ‘Statement’ to ‘Disclosure’ 

The new guidance introduces a shift toward “modern slavery disclosures.” This aligns reporting more closely with broader ESG and Social Value frameworks. Businesses must now provide granular data rather than vague aspirations.

Continuous improvement 

Static templates are no longer sufficient. Organisations are expected to demonstrate how their due diligence efforts are evolving. You must identify where interventions have succeeded, where they have failed, and how you plan to improve. 

Incident disclosure 

Previously, businesses often avoided reporting actual incidents for fear of reputational damage. The new guidance encourages the disclosure of actual modern slavery incidents and the subsequent remediation steps taken. Identifying and fixing an issue is now viewed as a sign of a functioning due diligence system, rather than a failure. 

Multi-tier accountability 

Main contractors can no longer claim that supply chain complexity is a valid excuse for lack of oversight. Transparency must extend beyond Tier 1 suppliers to subcontractors and agencies further down the chain.

 

Why eliminating slavery in construction matters 

The construction sector is particularly vulnerable due to lengthy supply chains, heavy use of temporary labour, and cost pressures. 

• Human cost: Behind the statistics are individuals. In 2024, the top three nationalities referred were UK (23%), Albanian (13%), and Vietnamese (11%). 
• Legal & financial risk: Failure to comply with the Modern Slavery Act can lead to unlimited fines and severe legal repercussions. 
• Reputational damage: Association with forced labour can cause irreversible damage to brand reputation and disqualify companies from public sector tenders. 

 

How we help main contractors ensure compliance 

For main contractors, the challenge lies in gaining visibility over a fragmented supply chain. Managing risk requires centralised data and verified suppliers. 

With Constructionline, you get: 

• Enhanced supply chain visibility: Our platform provides access to a network of 30,000+ verified construction subcontractors, ensuring you know exactly who is working on your projects. 
• Outsourced verification: Our Gold and Platinum subcontractor compliance memberships align with the Common Assessment Standard, which includes rigorous checks on modern slavery policies, right-to-work documentation, and ethical employment practices. 
• Risk mitigation: By centralising compliance data, our software allows procurement teams to identify high-risk suppliers before contracts are awarded to minimise supply chain risk. 

Discover more of our integrated construction supply chain solutions. 

 

How we help subcontractors secure work and combat modern slavery 

For subcontractors, demonstrating compliance with the Modern Slavery Act is a competitive advantage and often a prerequisite for winning work with Tier 1 contractors. 

With our subcontractor compliance memberships, you get: 

• Simplified pre-qualification: Completing your profile and achieving verified status (such as CAS) proves to main contractors that you meet the required ethical standards. 
• Reduced Admin Burden: Our platform reduces onboarding questions by approximately 50%, allowing you to provide your modern slavery compliance data once and share it with multiple buyers. 
• Market Access: Being part of a verified network increases visibility to top-tier main contractors looking for compliant supply chain partners.