Tax number

Steps

1. Make your residence application at the municipality (fact sheet BE-SEJOUR-TOUS-001). People entered in the population registers, the foreigners' registers or the waiting register are registered in the National Register.
2. The number is assigned to you at this first registration in the National Register. You have no separate application to make.
3. You will find it on your electronic card for foreigners (E or EU card). The NISS appears on the eID, on the electronic card of EU nationals, on the residence permit of non-EU nationals or on the isi+ card.
4. If you are not registered in a Belgian municipality but you work in Belgium: the BIS number is requested from the Crossroads Bank for Social Security, which assigns it, through the municipality or through an institution of the social security network. For casual workers without a NISS (agriculture and horticulture), the social security portal says to go first through the municipal administration of the place of residence.

Documents

• Those for your residence application at the municipality: identity document or passport, and documents linked to your situation (see BE-SEJOUR-TOUS-001).

Costs and timelines

• Number: no specific procedure or fee; it follows from your registration.
• Format: 11 digits in three groups: 6 digits for the date of birth (YYMMDD), 3 digits of sequence number, 2 check digits. For a BIS number, the month of birth is increased by 20 or by 40.
• Timeline: from your first registration by the municipality. The time to then obtain the electronic card varies by municipality.

Common pitfalls

• Looking for a separate "tax number". For an individual, the Belgian tax identification number has 11 digits (Official Journal of the EU, 2016/C 481/08), the same format as the National Register number. Do not confuse it with the business number (10 digits, starting with 0 for businesses already registered and with 1 for new ones since 19 September 2023, according to the SPF Économie), which concerns the self-employed and companies.
• Waiting for the card before starting work. Your employer needs your number (or a BIS number) to declare you. Talk to them about it as soon as you are hired.
• Keeping a BIS number after you settle in. Once registered in a municipality, it is your National Register number that counts.
• Changing address without telling the new municipality. Your registration, and so your National Register data, depend on it.

What changes by country of origin

• EU and EEA citizens: number assigned at the registration linked to annex 19.
• Swiss citizens: same procedure as EU citizens.
• British citizens (Scots included): same logic, but after registration as a third-country national (or as a beneficiary of the withdrawal agreement if they lived in Belgium before 2021). The NISS then appears on the residence permit.