What LIMOSA is
LIMOSA is the Belgian system for registering posted workers. Mandatory for every person sent to work in Belgium — regardless of length of stay or industry (with a few exemptions).
The registration is filed before work in Belgium begins, on the socialsecurity.be portal. Once registered, you receive an L1 — a document the worker must carry on them.
What you register
- Employer details (name, NIP, address).
- Worker details (name, PESEL/ID number, nationality).
- Workplace in Belgium (precise address — not just the city).
- Posting period (start and end dates).
- The Belgian client (their company).
- Industry.
Exemptions
LIMOSA registration is not required for:
- commercial postings of up to 5 days per calendar year,
- conference attendance without performing work,
- international transport without unloading in Belgium.
Each exemption has its own conditions — verify in borderline cases.
What you need beyond LIMOSA
- A1 certificate from ZUS (Polish social insurance — contributions stay in Poland).
- Belgian sectoral minimum wage (CCT 43) — often 2–3x higher than Polish minimums.
- Working time records — inspections are frequent, especially in construction.
Penalties
No LIMOSA filing means fines from EUR 1,600 to 6,400 per worker. Repeated breaches can lead to a ban on operating in Belgium.
Belgium is one of the most active enforcers of posting rules against Polish workers. LIMOSA filings leave no margin for error in documentation quality.