Non-Belgian employers whose staff work temporarily in Belgium are obliged to submit a so-called Limosa-1 declaration. This obligation also applies to cross-border commuters who live in Belgium and work (partly) from home for a foreign employer. The obligation to declare home offices was temporarily suspended during the pandemic. It has been in force again since 1 July 2022.
Employers whose employees work from home in Belgium are therefore again obliged to file this Limosa 1 declaration.
For more information on how to submit a Limosa-1 declaration, see: https://www.socialsecurity.be/site_de/agents/Applics/meldingsplicht/wie_melden.htm (English version not available)
Further information on Limosa for cross-border commuters: https://campaigns.eranova.fgov.be/r-b9f7c56ba01a4926bc9c27e61f188305041371679d177cc8