Flemish Duty of Care for Construction Projects in Belgium (2026): Practical Compliance Guide for Contractors, Clients and Subcontractors

Since 1 January 2026, every contractor, professional client and subcontractor engaged on a construction project in the Flemish Region has been subject to a new zorgvuldigheidsplicht, a statutory duty of care designed to combat illegal employment throughout the subcontracting chain. The Flemish duty of care in Belgium represents the most significant tightening of chain-liability obligations in the region’s construction sector in over a decade, and the Flemish authorities have signalled a six-month enforcement grace period that is rapidly drawing to a close.

This guide provides the practical compliance playbook that contractors, clients, in-house counsel and project managers need right now: a step-by-step breakdown of who must do what, which documents to collect, how to update construction contracts in Belgium, and what happens if you fall short.

Here is what this article delivers:

• Legal basis and scope of the new duty of diligence in Flanders
• Entity-by-entity obligation map, clients, main contractors, intermediary contractors, subcontractors
• Practical checklist of required documents and contractor due diligence steps
• 12-step compliance playbook from pre-tender through to final payment
• Sample contract clauses for chain-liability flow-down, audit access and indemnity
• Enforcement timeline, penalties and risk-management guidance
• Comparison table and FAQ for quick reference

What Is the Flemish Duty of Care (Zorgvuldigheidsplicht)?

Legal Basis and Definitions

The Flemish duty of care is a regional regulatory measure adopted by the Flemish Government to strengthen the fight against illegal employment, particularly the employment of third-country nationals without valid work permits, in sectors where subcontracting chains are long and opaque. It builds on the existing federal framework on chain liability for illegal employment but introduces Flemish-specific verification obligations, record-keeping duties and enforcement mechanisms that apply to any works or services performed within the Flemish Region.

The official Flemish guidance published on Vlaanderen.be defines chain liability for illegal employment as the mechanism through which principals, main contractors and intermediary contractors can be held jointly and severally liable when a subcontractor in the chain employs workers illegally. The new decree tightens the conditions under which that liability can be avoided: parties must now demonstrate that they have exercised a prescribed level of due diligence, the zorgvuldigheidsplicht, by proactively verifying the legality of their subcontractors’ workforce.

Key Terms

The Dutch term zorgvuldigheidsplicht (literally “duty of diligence” or “duty of care”) is the statutory label used in the Flemish decree. In practice, it requires each party in the contracting chain to carry out specific checks before engaging a subcontractor and to retain evidence of those checks for the duration of the contractual relationship and beyond. The obligation is distinct from the broader Belgian federal rules on social fraud because it imposes proactive, documented verification rather than merely prohibiting the use of illegal labour. Construction compliance in Flanders now demands an active administrative effort, not just passive good faith.

Who the Flemish Duty of Care Applies To, Entity Breakdown

The scope of the new duty extends across the full subcontracting chain. Understanding which entity bears which obligation is the starting point for every compliance programme. According to guidance published by Partena Professional, the rules target the following categories:

• Professional clients (project owners engaging contractors for business purposes). They must verify that the main contractor they engage is properly registered, employs workers legally and holds valid insurances. Where the client is a natural person commissioning works for purely private purposes, the obligations are lighter, though not entirely absent.
• Main contractors. They carry the heaviest burden. A main contractor must verify each direct subcontractor’s compliance status, collect and retain documentary evidence, and ensure that chain-liability protections flow down to every tier of subcontracting.
• Intermediary contractors. Any entity that sits between the main contractor and the workers performing the actual works bears the same verification duties towards its own subcontractors.
• Direct subcontractors. Subcontractors must be able to supply the required documentation on request, warrant the legal status of their workforce, and flow down equivalent obligations to any sub-subcontractors they engage.

High-Risk Sectors

While the decree applies broadly to construction and real estate works, industry observers expect enforcement to focus initially on the sectors historically most affected by illegal employment: building construction, renovation and demolition, industrial cleaning, scaffolding, roofing, and specialist finishing trades. Commentary from Van Havermaet International highlights that checks on non-EEA nationals are a particular enforcement priority, with inspectors likely to scrutinise work permits, single permits and the accuracy of Limosa declarations.

Required Checks, Documents and Recordkeeping, Contractor Due Diligence Checklist

The core of the Flemish duty of care obligation is documentary. Contractors and clients must be able to demonstrate that they have collected, verified and retained a defined set of documents for every subcontractor in the chain. Drawing on the official Flemish guidance and the practical checklists published by Claeys & Engels and Partena Professional, the following checklist captures the essential subcontractor checks in Belgium that every compliant organisation must implement.

Documents To Request from Each Subcontractor

Intake Form Fields, What to Collect at Onboarding

An effective subcontractor intake form should capture, at a minimum:

1. Full legal name, registered address and KBO/enterprise number
2. VAT identification number
3. Contact details (authorised representative, project lead)
4. Number of workers to be deployed, including nationality breakdown
5. Confirmation of whether any non-EEA nationals will be deployed (if yes, attach permits)
6. Name and contact details of any sub-subcontractors the subcontractor intends to engage
7. Signature block: warranty of compliance with all applicable employment, immigration and social security laws

Firms should treat this intake process as a condition precedent to the subcontractor starting work. No documentation, no site access, that principle, consistently enforced, is the single most effective defence in any subsequent inspection or chain-liability claim.

Step-by-Step Construction Compliance Playbook for Main Contractors and Clients

Compliance with the Flemish duty of care in Belgium is not a one-off exercise. It requires embedded processes from tender stage through to final account. The following 12-step playbook translates the legal requirements into operational reality for construction compliance in Flanders.

1. Pre-tender, embed compliance in procurement. Include the duty-of-care requirements in every request for quotation and tender document. State explicitly that subcontractors must provide all required documents before engagement.
2. Evaluate subcontractor eligibility. Before awarding a subcontract, run a KBO check, verify NSSO attestation status and confirm VAT registration. Flag any subcontractor with outstanding social security debts.
3. Collect and verify documents. Use the standardised intake form (above) to collect the full document set. Verify work permits against official databases where available.
4. Update subcontract agreements. Insert the sample clauses set out in the next section. Ensure the contract includes a flow-down obligation requiring the subcontractor to impose equivalent duties on its own sub-subcontractors.
5. Brief site management. Train site managers and foremen on what to check when new workers arrive: identity documents, work permits, Limosa confirmation. Provide a quick-reference card listing red flags (see box below).
6. Monitor during execution. Conduct periodic spot checks, at least quarterly and after every significant change in the subcontractor’s workforce. Refresh NSSO attestations every quarter.
7. Maintain a compliance register. Keep a centralised digital or physical register of all documents collected, organised by subcontractor and by project. Record the date each document was received and its expiry date.
8. Escalate promptly. If a spot check reveals an irregularity, an expired work permit, an unregistered worker, a missing Limosa declaration, suspend the subcontractor’s access to the site immediately and demand rectification within a defined period (48–72 hours is a practical benchmark).
9. Document every escalation. Keep written records of every suspension, rectification request and outcome. This paper trail is your evidence of active diligence in any enforcement proceeding.
10. Audit sub-subcontractors. Where your subcontractor engages its own subs, request evidence that the same checks have been carried out down the chain. Include a contractual right to audit this evidence.
11. Manage final payments. Before releasing final payments or retention, confirm that no chain-liability claims or social inspection findings are outstanding against the subcontractor.
12. Post-project archiving. Archive the full compliance file for a minimum of five years after project completion. Ensure files are accessible in the event of a retrospective inspection.

Red flags, indicators of potential illegal employment on site:

• Workers unable to produce identity documents on request
• Workers whose nationality and stated employer do not match the documentation on file
• Subcontractor unable or unwilling to provide NSSO attestation
• Workforce numbers on site materially exceeding the headcount declared at onboarding
• Workers present outside the validity window of a work permit or Limosa declaration
• Evidence of wage payments below applicable collective-agreement minima

Contract Drafting for Construction Contracts in Belgium, Sample Clauses and Practical Tips

Updating your standard construction contracts is not optional. The chain-liability provisions in Flanders mean that a main contractor or client who cannot show that its contracts incorporate adequate protections will find it significantly harder to defend against a joint-liability claim. The sample clauses below are starting points, they should be adapted to the specific project, jurisdiction and risk profile with the assistance of qualified counsel. For a comprehensive overview of construction law terminology, consult the Global Law Experts glossary.

Clause 1, Duty-of-Care Covenant

“The Subcontractor warrants that it has read, understands and will comply with the Flemish duty of care (zorgvuldigheidsplicht) as set out in [decree reference]. The Subcontractor shall, prior to the commencement of any Works and on an ongoing basis, provide to the Contractor all documents and information required to demonstrate compliance, including but not limited to identity documents, work permits, NSSO attestations and proof of insurance.”

Drafting note: Reference the specific decree or its Moniteur belge publication number. Avoid generic references to “applicable law”, specificity strengthens enforceability.

Clause 2, Flow-Down / Chain Provision

“The Subcontractor shall include provisions substantially equivalent to this Clause in all agreements with its own sub-subcontractors and shall ensure compliance throughout the subcontracting chain. The Subcontractor shall provide evidence of such inclusion upon request.”

Drafting note: This clause is the backbone of chain liability in Flanders compliance. Without it, liability gaps open at every tier.

Clause 3, Audit Access

“The Contractor (and/or the Client) shall have the right, on reasonable notice, to audit the Subcontractor’s records relating to the employment, immigration status, social security registration and insurance of all workers deployed on the Project. The Subcontractor shall cooperate fully with any such audit.”

Drafting note: Ensure the audit right extends to sub-subcontractor records. Negotiate a practical notice period (typically 5 business days) that balances thoroughness with operational reality.

Clause 4, Indemnity for Illegal Employment

“The Subcontractor shall indemnify and hold harmless the Contractor and the Client against all losses, liabilities, fines, penalties and costs arising from or in connection with any breach of applicable employment, immigration or social security laws by the Subcontractor or any of its sub-subcontractors, including but not limited to any chain-liability claim under the Flemish duty-of-care regime.”

Drafting note: Belgian courts generally uphold indemnity clauses between commercial parties, but gross negligence or wilful misconduct by the indemnified party may limit recovery. Pair this clause with the audit and escalation provisions to demonstrate active due diligence.

Clause 5, Suspension and Termination for Non-Compliance

“In the event that the Subcontractor fails to provide or maintain the required documentation, or where the Contractor has reasonable grounds to believe that workers are employed illegally, the Contractor may immediately suspend the Subcontractor’s right to perform the Works and, if the breach is not remedied within [5] Business Days, terminate this Agreement for cause without liability.”

Drafting note: The suspension right is the teeth of the compliance regime. Without it, detection of a problem leads only to a contractual dispute rather than an immediate operational remedy.

Clause 6, Document Retention

“Both Parties shall retain all documentation produced or collected pursuant to this Clause for a minimum period of five (5) years following practical completion of the Works, or such longer period as may be required by law.”

Enforcement, Penalties and Practical Risk Exposures

The consequences of non-compliance with the Flemish duty of care are both administrative and civil. According to Grant Thornton Belgium, the tightened chain-liability rules mean that a main contractor can be held jointly and severally liable for wages owed to illegally employed workers engaged by a subcontractor further down the chain, as well as for social security contributions, administrative fines and, in serious cases, criminal prosecution for aiding or facilitating illegal employment.

The practical risk exposures include:

• Joint and several liability for unpaid wages and social security contributions of illegally employed workers
• Administrative fines imposed by Flemish labour inspectors
• Exclusion from public procurement, a finding of illegal employment can trigger mandatory or discretionary exclusion grounds under Belgian public procurement law
• Reputational damage, inspection findings are increasingly publicised, and large-scale construction projects attract media scrutiny
• Project delays, a site shutdown order following an inspection can halt works for days or weeks

Industry observers expect the Flemish labour inspectorate to ramp up targeted enforcement following the expiry of the grace period, with an initial focus on large-scale residential and infrastructure projects in the greater Antwerp and Brussels periphery corridors.

Timeline, Grace Period and Immediate Actions

The implementation calendar for the Flemish duty-of-care regime can be summarised as follows:

Immediate 30 / 60 / 90 day tasks:

• Within 30 days: Audit all current subcontractor files. Identify documentation gaps. Issue requests for missing documents.
• Within 60 days: Update standard subcontract templates with the sample clauses above. Brief all site managers and procurement staff.
• Within 90 days: Implement a centralised compliance register. Conduct a dry-run audit on at least one active project. Rectify any deficiencies found.

Comparison Table, Obligations by Entity Type Under the Flemish Duty of Care in Belgium

Conclusion, Achieving Construction Compliance in Flanders

The Flemish duty of care in Belgium is not a paper exercise, it is an operational obligation that touches procurement, site management, contract drafting and archiving. With the six-month grace period drawing to a close, every contractor, client and subcontractor active in the Flemish Region should treat the next 90 days as the final window to close compliance gaps. Audit your subcontractor files, update your construction contracts, train your teams and build the compliance register. For those seeking qualified legal counsel on construction, real estate or chain-liability matters in Belgium, the Global Law Experts lawyer directory connects you with specialists across the jurisdiction.

This article is published for general informational purposes and does not constitute legal advice. Readers are encouraged to consult qualified legal counsel for guidance specific to their projects and circumstances. To learn more about Global Law Experts or to get in touch, visit the linked pages.

Sources

1. Vlaanderen, Chain Liability for Illegal Employment (Official Guidance)
2. Partena Professional, Flanders Introduces Duty of Diligence for Contractors (2026)
3. Lexgo, Be Ready for the Flemish Duty of Care Obligation in the Construction Sector
4. LegalDirect, Zorgvuldigheidsplicht en Ketenaansprakelijkheid
5. Claeys & Engels, Update: Flemish Region Amendment to Chain Liability Regulations
6. Grant Thornton Belgium, New Flemish Rules on Chain Liability (2026)
7. Van Havermaet International, New Obligations: Checks When Employing Non-EEA Nationals in Flanders