Your subcontractor’s compliance failure is your fine. Here is how to protect yourself.
In Belgian construction, the main contractor sits at the top of the liability chain. When a subcontractor fails to register workers correctly on site, the legal and financial consequences do not stop with the subcontractor, they cascade upward. Chain liability (hoofdelijke aansprakelijkheid) means that you, as the main contractor, can be held responsible for registration failures, unpaid social contributions, and safety violations committed anywhere in your subcontracting chain.
With the CIAW (Check in at Work) system already mandatory on most construction sites and the broader 2027 time registration obligation approaching, the stakes are higher than ever. This article explains your legal exposure, the registration obligations you must enforce, and the practical steps you can take to stay compliant.
Quick Navigation
- What Is Chain Liability in Belgian Construction?
- CIAW Registration: Your Legal Obligations as Main Contractor
- The Risks of Non-Compliance
- How to Protect Yourself: A Practical Framework
- Digital Solutions: Centralised Registration for the Entire Chain
- The 2027 Mandate: What Changes for Main Contractors?
- Frequently Asked Questions
What Is Chain Liability in Belgian Construction?
Chain liability in the Belgian construction sector means that each party in the contracting chain shares responsibility for the obligations of the parties below them. This principle is codified in Belgian social legislation and enforced by the NSSO (RSZ/ONSS).
In practical terms:
- If a subcontractor fails to register workers under CIAW, the main contractor can be fined.
- If a sub-subcontractor has unregistered workers on site, liability flows upward through every party in the chain.
- The main contractor has a legal duty to verify that all parties in their chain comply with registration and social security obligations.
⚠️ Chain liability is not limited to direct subcontractors. If you hire Subcontractor A, and they subcontract to Company B, and Company B fails to register workers, you, the main contractor, remain liable.
CIAW Registration: Your Legal Obligations as Main Contractor
The CIAW system requires electronic registration of all workers on construction sites that meet specific thresholds. As main contractor, your responsibilities extend beyond your own employees.
| Situation | CIAW Required? | Main Contractor Responsibility |
| No subcontractor, project >EUR 500,000 | Yes | Register own employees |
| 1 subcontractor, project >EUR 5,000 | Yes | Register own + verify subcontractor registration |
| 2+ subcontractors, any value | Always | Register own + verify all subcontractor registrations |
| Sub-subcontractors present | Always | Full chain verification required |
Each unregistered worker can result in fines of up to EUR 6,000 per worker per day. For a site with 10 unregistered subcontractor workers over just one week, the exposure can exceed EUR 300,000.
⚠️ CIAO (Check In AND Out) is already active for the cleaning sector since 2025 and is expected to extend to construction. This will require both entry AND exit registration, doubling the data points the main contractor must verify.
The Risks of Non-Compliance
The consequences of failing to manage chain registration compliance go well beyond fines.
| Risk Category | Impact |
| Financial penalties | Up to EUR 6,000 per unregistered worker per day |
| Joint liability for social contributions | Main contractor can be required to pay unpaid NSSO contributions of subcontractors |
| Project delays | NSSO inspections can halt site operations pending investigation |
| Reputational damage | Public procurement exclusion, loss of client trust |
| Insurance complications | Non-compliant registrations may void site liability coverage |
| Criminal prosecution | Repeated or wilful violations can lead to criminal charges against directors |
“We had always assumed our subcontractors handled their own registrations. One NSSO inspection changed that assumption, and it cost us six figures.”– Operations Director, Belgian main contractor (100+ employees)
How to Protect Yourself: A Practical Framework
Managing chain liability is not about micromanaging subcontractors. It is about creating systems that make compliance automatic and verifiable.
1. Contractual Requirements
Include explicit CIAW compliance clauses in every subcontractor agreement. Require subcontractors to use your designated registration system or demonstrate integration with it. Define penalties for non-compliance.
2. Centralised Registration System
Deploy a single registration platform across the entire site that all contractors and subcontractors use. Suivo’s
time registration solution supports multiple registration methods (app, badge, site pole) so every worker, regardless of employer, can register through the same system.
3. Real-Time Monitoring
Paper-based verification is retrospective, you discover problems after they have already occurred. A digital dashboard that shows live registration status per contractor allows you to identify gaps the moment they happen.
Explore Suivo’s Check-in at Work solution →
4. Regular Audits
Schedule weekly reviews of registration data. Cross-reference the number of registered workers per subcontractor against their declared workforce. Flag discrepancies immediately.
5. Chain Documentation
Maintain a complete and up-to-date record of your subcontracting chain: who hired whom, contract values, and registration responsibilities. The NSSO can request this documentation during an inspection.
Digital Solutions: Centralised Registration for the Entire Chain
The most effective way to manage chain liability is to remove the dependency on individual subcontractor compliance. When every worker on site registers through a single, centralised system, the main contractor has full visibility.
| Feature | Benefit for Main Contractor |
| Single registration platform for all contractors | One dashboard, one source of truth |
| Multiple registration methods (app, badge, site pole) | No barriers for subcontractor workers |
| Automatic CIAW reporting to NSSO | Compliance handled in the background |
| Real-time alerts for missing registrations | Gaps identified before inspections do |
| Exportable audit trail | Ready documentation for NSSO or client audits |
| Subcontractor management view | Per-contractor compliance scores and worker lists |
See how Suivo works for construction →
The 2027 Mandate: What Changes for Main Contractors?
From January 2027, all Belgian employers must have an objective, reliable system for recording daily working hours. While CIAW covers attendance registration on construction sites, the 2027 mandate broadens the scope to include actual working hours, start times, end times, and breaks.
For main contractors, this means:
• Your own time registration system must record hours, not just presence.
• Subcontractor compliance will also need to cover working time records.
• Integration with payroll systems (SD Worx, Partena, Acerta) becomes critical to ensure hours flow accurately from site to salary slip.
⚠️ The 2027 mandate is not a replacement for CIAW, it is an addition. Construction sites will need both attendance registration (CIAW) and working time records. Plan your systems accordingly.
Read the full time registration construction guide →
Frequently Asked Questions
Can a main contractor be fined for a sub-subcontractor’s violation?
Yes. Chain liability extends through the entire subcontracting chain. If a sub-subcontractor has unregistered workers, the main contractor can be held jointly liable for fines and unpaid social contributions.
Does including a CIAW clause in contracts eliminate liability?
Contractual clauses provide a basis for recovering costs from the subcontractor, but they do not eliminate the main contractor’s legal liability toward the NSSO. You remain responsible for ensuring compliance on your site.
What if a subcontractor refuses to use my registration system?
This is a red flag. If a subcontractor cannot or will not comply with your registration requirements, consider whether the business relationship is worth the legal and financial risk. Many main contractors now make system adoption a condition of the contract.
Learn more about CIAW requirements →
How does Suivo handle subcontractors with their own registration system?
Suivo offers API integrations that can connect to existing systems or receive data from third-party platforms. The goal is a single dashboard for the main contractor, regardless of which tool each subcontractor uses at the point of registration.
What documentation should I prepare for an NSSO inspection?
Have ready: a complete subcontracting chain overview, CIAW registration logs for the inspection period, worker lists per contractor, and evidence that your registration system is operational and covers all workers on site.
Related reading:
Best Digital Time Registration Tools in Belgium (2026)
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