You can either vote in Belgium or your country of origin.
In Belgium, all residents who have the nationality of an European Union member state and who:
are registered in the population or foreigners register no later than 28 February 2019 or hold a special identity card;
are at least 18 years old on the date of the election (26 May 2019);
complete the VOTER FORM (see "media" below) for the elections no later than28 February 2019.
Notice for United Kingdom nationals: if ‘Brexit’ takes place before 26 May 2019, and you are registered to vote in Belgium, your registration will be cancelled because you will no longer meet the nationality requirement.