Registering your residence abroad – Belgium
UK decision to invoke Article 50 of the TEU: More information
You must register your residence within 3 months of arrival. You can do so at the town hall.
Inactive citizens (pensioners, self-sufficient persons) must provide proof of health insurance and sufficient resources.
You must carry your registration certificate at all times.
If you don't register your residence, you could incur a 200 euro fine
For more information, check with the town hall where you live.
More on residence rights and formalities.