If you engage a foreign subcontractor on a Belgian construction project and their compliance fails, the financial consequences do not stay with them. You can become jointly and severally liable for their workers’ unpaid wages, you may be obliged to withhold part of every invoice and pay it directly to the authorities, and you carry a duty to report any posted worker who cannot produce a LIMOSA-1. None of this depends on you having done anything wrong. This article covers what the exposure actually is and how to screen for it before you award the work.
Why the risk sits with you
Belgium’s enforcement approach for social dumping deliberately puts responsibility on the party with the commercial relationship, because that is the party able to apply pressure. Three separate mechanisms do the work.
1. Joint and several liability for wages
According to the Federal Public Service Employment, in construction-related activities the client who calls in a contractor is jointly and severally liable for paying the wage due to workers employed by that contractor.
The scheme covers the client in a direct contractual relationship with a contractor-employer, and the contractor or intermediate contractor in a direct contractual relationship with a subcontractor-employer, whether or not there is a longer chain behind them.
For subcontractors further down the chain, liability is triggered by notification. Where the Inspectorate notifies you in writing that a subcontractor operating indirectly below you has seriously failed to pay proper wages, you become jointly and severally liable for those wages once summoned by registered letter. A notification you ignore is a bill you have accepted.
2. The withholding obligation
If your contractor or subcontractor has outstanding debts, you must not simply pay their invoice in full.
| Debt type | You withhold | Paid to |
|---|---|---|
| Social security debts | 35% of the invoice excluding VAT | NSSO |
| Tax debts | 15% of the invoice excluding VAT | FPS Finance |
| Self-employed social contributions (since 1 May 2026) | 15% of the invoice excluding VAT | The self-employed social insurance body |
You check the position at checkinhoudingsplicht.be before paying. If you fail to withhold when you should have, you risk an administrative fine and can be held liable for the debts themselves. In other words, paying a subcontractor’s invoice in full without checking can mean paying part of it twice.
For foreign subcontractors without a Belgian VAT number, the check works differently and you may need to request confirmation directly from the Belgian authorities. Build the extra time into your payment process rather than discovering it on the due date.
3. The duty to report
If a posted worker cannot produce their LIMOSA-1, the Belgian principal or client has to report this to the Belgian government. The obligation falls away only where the principal is a natural person engaging workers for strictly private purposes, which is not the situation on a commercial site.
This is worth understanding correctly: it is not a discretionary courtesy to the authorities. It is an obligation on you, triggered by your subcontractor’s omission.
What this costs when it goes wrong
Failing to file a Limosa declaration is a level 4 offence under the Belgian Social Criminal Code, the heaviest category, carrying the possibility of imprisonment alongside financial penalties.
The financial exposure increased on 1 February 2026, when the Act of 19 December 2025 raised the multiplier applied to social criminal fines from 8 to 10, an increase of 25 percent. Published fine tables differ on the exact euro ranges depending on which multiplier basis they show, so take advice rather than budgeting from a headline figure. Where aggravating factors apply, the fine may not fall below half the statutory maximum. For some infringements the amount is multiplied by the number of workers involved, up to a maximum of 100.
Then there is the cost nobody itemises: a site stopped mid-inspection while the paperwork is sorted out, on a project with liquidated damages running.
How to screen a foreign subcontractor before award
Most of this exposure is manageable if you do the checks at the right moment, which is before you award rather than after the first invoice.
At tender stage, ask for:
- Proof of A1 certificates for the workers they intend to deploy, with dates covering your programme. See A1 certificates for Belgium.
- Confirmation that they will file Limosa declarations before mobilisation, and the name and contact details of their Belgian liaison person.
- The check result from checkinhoudingsplicht.be for social and tax debts.
- A named person responsible for daily presence registration on your site.
Write into the contract:
- Who performs Check-in-at-Work registration each day. Responsibility for registration lies both with the party sending the worker and the party doing the work, and the two must agree who registers and verify that it happened. Leaving that to assumption is how sites end up with nobody registering.
- An obligation to notify you of any crew change before it happens, with updated documentation.
- A right to withhold payment where documentation is missing.
During the works:
- Re-run the debt check before each payment, not once at the start.
- Reconcile who was actually on site against who was declared, weekly rather than at project close.
- Watch A1 and Limosa end dates against your programme, and flag overruns early.
Check-in-at-Work is the daily control
The registration obligation applies to works on immovable property, excluding cleaning, where the total value reaches 500,000 euro excluding VAT, and to specified meat-sector activities. Registration must occur before the person begins work, daily, for each working day.
From 1 April 2027, a Programme Law adopted on 30 May 2026 extends this to registering both entry and exit, and adds the supply of ready-mixed concrete to the scope. If your current arrangement is a sign-in sheet at the gate, that will not carry you past that date.
Practically, this is also your best evidence. A per-worker, per-day digital record of who was on your site, tied to the subcontractor that sent them, is what lets you answer an inspector’s question in minutes and demonstrate that you exercised control. Where the main contractor provides the registration system to subcontractors, as the rules envisage, you get one consistent record instead of relying on each subcontractor’s own arrangements.
Suivo’s check-in-at-work is built for exactly that situation: one site, several subcontractors, one attendance record, available without reconstructing anything. It runs on the same workforce management platform as your own time tracking, so compliance data and hours are not two separate systems.
See how B&R Bouwgroep runs registration across their projects and subcontractor base.
To send a subcontractor the requirements that apply to them, point them at the compliance hub for foreign employers.
Honest advice on where to spend the effort
Not every project needs the full apparatus. A single specialist technician visiting for two days under a genuine exemption is a different risk from a twenty-person foreign crew on a nine-month programme.
Scale the screening to the exposure. What is not optional, on any project with foreign crews above the registration threshold, is knowing who was on your site each day and being able to prove it. Everything else in this article is easier to defend once that record exists.
Book a free demo
If you work with foreign subcontractors on Belgian sites, we will show you how to get one reliable attendance record across every party on the project. Book a free demo.
