A Belgian friend once described the national number as "the number that follows you from the maternity ward to the pension office." It is a fair summary. In Belgium, one 11-digit number is used by your employer, your health fund, the tax office and your bank. For a newcomer, the good news is that there is no separate application: the Belgian national number comes with your registration at the commune.
What is the Belgian national number?
It is the identification number given when you are entered in the National Register, the database that holds the population registers kept by communes. Its format is a date of birth (six digits, year-month-day), a three-digit serial number and two check digits. It also serves as your social security number, known as the NISS (numéro d'identification de la sécurité sociale).
How do you get the Belgian national number?
- Apply for residence at your commune. Our guide to residence in Belgium for EU citizens explains how.
- When the commune enters you in the register, in the population register, the foreigners' register or the waiting register, the number is attributed.
- You find it on your electronic foreigner's card. It may take some time to receive the card, and the delay varies by commune.
There is no fee for the number itself. The card is charged by the commune.
Is it also your tax number?
Yes in practice. The Official Journal of the EU lists the Belgian tax identification number for individuals as an 11-digit number, the same format. Searching for a separate "Belgian tax number" is a common newcomer mistake. The tax office, SPF Finances, uses your national number.
Do not confuse it with the enterprise number, which has 10 digits and starts with 0. It concerns self-employed people and companies.
What is a BIS number?
If you work in Belgium without being registered in a Belgian commune, for instance as a cross-border worker, you receive a BIS number instead. It has the same format, with the month of birth increased by 20 or 40. The commune or the employer asks the Crossroads Bank for Social Security to assign it. For occasional workers without a NISS, the social security portal says to go first through the municipal administration of the place of residence.
Once you register in a commune, your national number replaces the BIS number for good.
Can you start work before the card arrives?
Your employer needs a number to declare you, either a national number or a BIS number. Mention it when you accept the job. Do not wait for the plastic card.
If your job starts before your commune appointment, or you commute from another country, which number applies to you is not always obvious. Moovy can tell you which one your employer should use and what to ask your commune.
What do you use it for?
- Your employer's declaration of your employment.
- Your health fund affiliation. See health insurance in Belgium.
- Your online access to government services. See the section on Mon DOSSIER in moving to Belgium.
- Your tax return, where the tax office identifies you by your national number.
- Your bank, which may ask for it with your identity papers: bank account in Belgium.
What mistakes should you avoid?
- Looking for a separate tax number. There is none for individuals.
- Keeping the BIS number after you settle. Use the national number once you are registered.
- Moving without telling the new commune. Your data in the National Register depends on your address.
- Sharing the number carelessly. It opens many doors. Give it to employers, public bodies and health funds, not to anyone who asks.
The national number is the first thing you will quote in almost every procedure. Once it is attributed, the rest of the list in moving to Belgium gets much faster.
How is the Belgian national number built?
The format tells you something. Six digits give the date of birth in year-month-day order, three digits are a serial number, and two digits are a check. For a BIS number the month of birth is increased by 20 or 40, which is how administrations tell the two apart. Because it contains your birth date, your Belgian national number is a sensitive piece of information. Keep copies of your card safe.
Where does the Belgian national number appear?
It appears on your electronic foreigner's card (E card, sometimes called EU card). The NISS is also printed on the eID, on the electronic card of EU nationals, on the residence permit of non-EU nationals or on the isi+ card. You will be asked for it by your employer, by your health fund, by banks and by most public services. When you fill in a tax return, it is also the identifier the tax office uses.
What if you have not been registered yet?
You may need a number before the commune has finished your file, for example if your job starts quickly. The commune or your employer can request a BIS number from the Crossroads Bank for Social Security. This is common for people who work in Belgium but live elsewhere, such as cross-border workers. Tell your employer which situation applies, so that the correct number is used for your declaration to social security.
Is the number linked to your address?
Your data in the National Register depend on your registration at a commune. If you move, tell the new commune, which updates your record. If you leave Belgium, deregister. Your tax mail and many official letters follow the address in the register, so an outdated record can mean missed letters and deadlines.
What can you do online with it?
With your electronic card, a card reader and your PIN, you can log in to Mon DOSSIER, the application of the National Register. It lets you consult your data, report an error, see which bodies consulted your data in the last six months and download or print certificates free of charge, including civil status records issued after 31 March 2019. Other digital keys, such as itsme, MyGov.be or a security code, can be activated, but the electronic card is the most secure key. Citizens of other EU countries can also log in through eIDAS with their national electronic identity; on first connection you need your national or BIS number, an email address and a phone number.
Understanding your Belgian national number early saves many phone calls. If you are about to register, read residence in Belgium for EU citizens and check that you have the right documents.
What if the number does not appear on your documents?
The commune or the employer can tell you which number was attributed to you. If you registered recently and you have only the annex 19 or the annex 8 certificate, ask the commune to confirm your number in writing. Do not guess or reuse a number from another country: an incorrect number delays your declaration to social security and your health fund affiliation.
Does the number change?
Normally no. Your national number stays the same for life. If you are first registered under a BIS number and later settle in Belgium, you receive a national number and the administration links the records. Keep a note of both numbers in case an old file still uses the BIS number.
How should you protect it?
Your national number appears on your card and opens many services. Give it only to bodies that need it, keep the PIN and PUK letter safe, and use official portals when you log in. If you lose your card, report it to the commune, which issues a replacement.