If your company is established outside Belgium and you send people to work there, four obligations apply and they stack rather than replace each other: an A1 certificate so your workers stay in their home social security system, a Limosa declaration filed before the first day of work, Check-in-at-Work presence registration on qualifying sites, and a named liaison person the Belgian Labour Inspectorate can reach. This page is the map. Each section links to the detail, and there is a guide for each of the twenty main countries that send workers into Belgium.
Start here: the four obligations
| Obligation | What it answers | Who files | When |
|---|---|---|---|
| A1 certificate | Which country’s social security applies? | You, to your home institution | Before departure |
| Limosa | Does Belgium know your worker is here? | You, at limosa.be | Before work starts |
| Check-in-at-Work | Who was on this site today? | Sender and worker, by agreement | Before work begins, daily |
| Liaison person | Who can Belgium contact? | You, to the Labour Inspectorate | Before the posting |
Read the two foundational guides first:
- Limosa declaration in Belgium: the complete guide covers who must declare, what information you need, the exemptions, and what happens if you skip it.
- Limosa, Dimona or Check-in-at-Work: which applies to you? is the decision path if you are not sure which systems you fall under.
The supporting detail
- A1 certificates for Belgium: what inspectors actually check. Why an A1 never replaces Limosa, and the identity, employer and date checks an inspector runs on site.
- Limosa exemptions: when you do not need to declare. The full list with exact day limits. The 8-day assembly exemption and the 5-day repair exemption are the two most often misread.
- Foreign subcontractors in Belgium: the liability that lands on the main contractor. Written for the Belgian side of the contract, and the fastest way to understand why your client asks for your paperwork.
The three things most companies get wrong
An A1 does not replace Limosa. They answer different questions and are issued by different bodies. You generally need both, and an inspector will ask for both.
Check-in-at-Work is daily, and the threshold is not yours to control. Registration is mandatory for works on immovable property, excluding cleaning, and certain meat-sector activities, where the total value of the works reaches 500,000 euro excluding VAT. That attaches to the works as a whole, so a small scope on a large site is still inside the obligation. Responsibility lies both with the party sending the worker and the party doing the work, and the two must agree who registers and verify it happened.
Foreign employers need Belgian portal access and a company number (CBE) to register presence at all. This has a lead time, and the obligation applies from the first working day, so discovering it on arrival means you are already late.
One change to plan for: a Programme Law adopted on 30 May 2026 extends registration to checking in and out, adds the supply of ready-mixed concrete, and enters into force on 1 April 2027.
Country guides
Limosa is filed by the posting company’s country of establishment, not the worker’s nationality. That distinction matters: the two largest third-country routes into Belgium are Ukrainians posted from Poland and Brazilians posted from Portugal, both into construction. Find your company’s country below.
The largest sending markets
- Polish companies working in Belgium. The largest source by far, and 55 percent of all construction posting companies.
- Dutch companies working in Belgium. Second largest, and dominant in petrochemical, electrical and metalworks.
- Portuguese companies working in Belgium. Construction-heavy, with a large third-country nationality share.
- French companies working in Belgium. Strong in electrical installation and petrochemical maintenance.
- German companies working in Belgium. Industrial and plant work, and the 8-day assembly trap.
- Romanian companies working in Belgium. Construction crews on longer programmes, with rotation risk.
- Lithuanian companies working in Belgium. Why the Limosa numbers fell without the work going away.
Established and growing markets
- Luxembourg companies working in Belgium. Cross-border normality is not an exemption.
- Slovenian companies working in Belgium. Only one in ten posted persons is a national.
- Slovak companies working in Belgium. Four in five construction postings are self-employed.
- Italian companies working in Belgium. Specialist teams on high-value industrial sites.
- Spanish companies working in Belgium. Entering a market with no established playbook.
- Czech companies working in Belgium. Self-employed status and the 5-day misreading.
- Bulgarian companies working in Belgium. Long programmes and expiring certificates.
- UK companies working in Belgium. Now a third-country employer, with an immigration layer on top.
Smaller and emerging markets
- Hungarian companies working in Belgium
- Croatian companies working in Belgium
- Irish companies working in Belgium
- Latvian companies working in Belgium
- Estonian companies working in Belgium
Common questions
Do I need a Limosa declaration for a one-day job? Yes, unless the activity falls squarely inside a specific exemption. There is no minimum number of days and no grace period. The declaration must exist before the work starts.
We have a valid A1. Is that enough? No. The A1 settles which social security system applies to your worker. Limosa notifies Belgium that they are working on its territory. Different bodies, different purposes, and you generally need both.
Who registers presence, us or the main contractor? Responsibility lies with both the party sending the worker and the party doing the work. The two must agree who registers and then verify it happened. Put that agreement in writing before mobilisation rather than assuming the main contractor covers you.
Our scope is small. Does the 500,000 euro threshold still catch us? Yes. The threshold attaches to the total value of the works, not to your contract. A modest scope on a large site is inside the obligation.
How long does a Limosa declaration last? A single notification can cover an anticipated duration of up to 24 months, and can be extended if the assignment runs longer than declared.
What happens if a worker on site is not the worker on the declaration? That is the single most common inspection finding. The declaration, the A1 and the daily site registration all name individuals, so a crew substitution that updates only your internal roster puts the three records out of step. Treat every rotation as a paperwork event, before travel.
Do we need a Belgian entity? Not to post workers, but you do need a Belgian company number (CBE) and secure access to the Belgian social security portal in order to perform Check-in-at-Work registration. Arrange it before mobilisation.
Does any of this apply to road transport? Road transport postings are declared through the EU portal for road transport rather than Limosa, and international transport is an exempt category. That exemption does not extend to cabotage in non-road sectors, nor to loading, installation, warehousing or site work performed in Belgium.
What it costs to get wrong
Failing to file a Limosa declaration is a level 4 offence, the heaviest category in the Belgian Social Criminal Code, carrying the possibility of imprisonment alongside financial penalties. Fines rose on 1 February 2026, when the Act of 19 December 2025 raised the multiplier applied to social criminal fines from 8 to 10. For some infringements the amount is multiplied by the number of workers involved, up to a maximum of 100.
Your Belgian client carries exposure as well. Under Belgium’s joint and several liability rules for construction-related activities, a client can be liable for wages owed to a contractor’s workers. Where a contractor has social or tax debts, the client must withhold 35 percent of each invoice excluding VAT for social security debts and 15 percent for tax debts, checked at checkinhoudingsplicht.be. Since 1 May 2026 a further 15 percent applies for outstanding self-employed contributions.
That is why Belgian main contractors increasingly screen foreign subcontractors before award rather than after the first invoice.
Making it work day to day
The rules are learnable. What is hard is keeping the file in your home office and the reality on a Belgian site in agreement, week after week, as crews rotate and programmes move.
Two habits carry most of the load. Treat every crew change as a compliance event, because the declaration, the A1 and the site registration all name individuals, and a substitution that updates only the internal roster puts the three records out of step. And capture presence digitally at the moment someone arrives, tied to the person and the project, so the site record matches your declarations by default and a specific past day can be produced on request without reconstructing it.
Suivo’s check-in-at-work is used on Belgian sites where several subcontractors work side by side, and runs on the same workforce management platform as time tracking, so the data captured for compliance also feeds hours and project costing instead of sitting in a separate system.
See how Cegelec manages registration across multiple Belgian sites.
Book a free demo
Tell us where your crews are working and which obligations apply, and we will show you what compliant registration looks like day to day. Book a free demo.
