Why you should register
Having your name registered in the population register kept by a Belgian consulate or embassy abroad entitles you to benefit from the same services as those provided by municipal authorities in Belgium, i.e. the management of your administrative file. Registering allows the embassy or consulate to assist you more efficiently when issuing an identity card, issuing consular certificates (e.g. residence certificates, registration certificates, certificates of nationality, 'household composition' certificates, cohabitation etc.). You may also participate in some elections in Belgium (federal general elections, and European elections if you reside in an EU Member State).
Foreign nationals who are part of your family may also be entered in the relevant population registers. However, registration does not entitle them to obtain a consular identity card or a passport, nor does it give them the right to be registered as a Belgian voter. If they require consular assistance, they should contact the office representing their country of origin.
By keeping your file up to date you will enable the embassy or consulate to help you more immediately, including in situations when you need emergency humanitarian aid (e.g. accidents, natural disasters, evacuations, and so on).