Applying for a national registration number

To be able to work as a foreign national in Belgium, you will require a social security identification number (INSS). This number is received automatically after registering at the Immigration Office, or upon registration with a health insurance provider. 

You need a national registration number or BIS number to receive a salary and accumulate social security rights.

The structure of the national registration number is YYMMDD-nnn-cc:

• YY = the last two digits of your year of birth
• MM = the two digits of your month of birth
• DD = the two digits of your day of birth
• nnn = sequence (uneven for men, even for women)
• cc = verification number

For example, if you were born on May 6 1966, your national registration number - and INSS number – will begin with 660506.

People without a Belgian nationality will receive a BIS number. This number has the same structure as the national registration number, but the third and fourth number of the month of birth are being topped up with 40 when the sex is known on the moment the number is granted, and topped up with 20 if the sex is not known on the moment the number is granted.

If you were born on May 6 1966, your BIS number will begin with 664506.

Once you have been assigned a permanent national registration number, inform your dedicated HR officer from the UAntwerp by sending them a copy of your residence permit.


International Staff Office Campus Middelheim - building C
Middelheimlaan 1
2020 Antwerp
Tel. +32 (0)3 265 31 49