Working off the books is working as a non-Belgium in Belgium, without permission to work in Belgium. If you’re not Belgian, and not a citizen of an EU member state, you must be given permission by the government to work here. There are some foreigners who don’t need this permission. For all others – and certainly if you come from a country outside of the European Union – you must obtain permission. If a person has no residence card, they cannot obtain this permission. If you work without this permission, you are working ‘illegally’. Your employer may be penalised. Work off the books is almost never registered with the government by the employer. If you are working, even though you have no legal residence, you’re probably working off the books.