Conservation of Belgian nationality
According to article 22 §1, 5° and 2 of the Belgian Nationality Code, if:
1. you were born outside Belgium, after 01.01.1967, and
2. you have never resided in Belgium between the age of 18 and 28, and
3. you have another nationality in addition to the Belgian nationality,
you will automatically lose the Belgian nationality on your 28th birthday unless either a passport or ID card has been issued to you between the ages of 18 and 28.
Therefore, if you have not applied for a passport or identity card between the ages of 18 and 28, the Consulate-General strongly recommend, in order to avoid the loss of your Belgian nationality, that you apply for either a passport or an ID card.