What’s a Belgian national number and BIS?

Belgian national number is one of the first things you need when moving to Belgium. Find out what it is and how you get one.

Angelina

2 minute read

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Updated on 20 Dec 2024

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Living

If you’re going to earn a salary in Belgium, pay taxes, access the social security or simply reside there for an extended period of time, your Belgian national number is one of the first things you must obtain. Luckily, it’s incredibly easy to do so!

But first things first!

The Belgian national number (numéro de registre national/rijksregisternummer) is a unique set of digits that’s used to identify persons registered in the population and foreigner’s registers held by the Belgian municipalities. It’s used to find administrative information about a person’s residence, civil status, nationality etc.

Basically, your Belgian national number (NN) is

your Belgian tax identification number, registration number, and social security identification number (NISS/INSZ) – all in one!

Anyone who’s planning to move to Belgium for longer than 90 days needs a Belgian national number.

You need your Belgian national number to:

• work in Belgium
• set up a business
• pay taxes in Belgium
• get a health insurance
• open a Belgian bank account
• make large purchases (e.g. real estate or car)
• get a Belgian driving licence
• set up utilities
• register for social security
• use online e-gov services

In other words, you need your Belgian national number to perform any activity that concerns the Belgian government.

Your Belgian ID can differ depending on your residence status:

1. All Belgian residents are assigned a national registration number.

2. Foreign nationals who work but do not live in Belgium (frontier workers) and foreign employees who stay in Belgium for less than 3 months get a BIS number.

Similarly, businesses operating in Belgium must obtain a unique business number (also CBE number or BCE in Dutch and KBO in French ). This 10-digit number is issued during registration at the Crossroads Bank for Enterprises (Kruispuntbank van Ondernemingen) and serves as a business tax number (VAT) in Belgium.

You can find your Belgian national number on:

• the front of your Belgian identity card
• the front of your EU card
• the back of your foreigner’s residence card
• your tax assessment
• your pension file

Your Belgian national number consists of 11 digits in the following format: YY.MM.DD-XXX.XX

• the first 6 digits are your date of birth (for BIS, the number of the month is increased by 40 if gender is known and 20 if unknown)
• the next 3 digits__ are used to differentiate people born on the same day (odd numbers for men and even numbers for women)
• the last 2 digits are a verification number calculated from the previous 9 digits.

The tax identification number in Belgium is issued to all residents automatically upon their registration in the national or foreigner’s register.. Convenient isn't it?

So, Belgian citizens get their national registration number at birth while foreigners receive their registration number when registering their address in the municipality and applying for a residence permit.

Don’t forget that third-country nationals must register in the town hall within 8 days from their arrival!

You can register at the city office by making an appointment through an online form or by emailing your local municipality.

Normally, you’ll need to submit your:

• valid identity card or passport scans
• rental contract
• EU citizens: depending on immigration status, proof of income, employment contract, marriage certificate etc.
• non-EU citizens: work permit / annex 46 / annex 47 or proof of solvency and enrolment certificate for students

As soon as you’ve registered with your local town hall, you’ll be assigned your NISS social security number) and Belgian tax identification number and considered a resident for tax purposes.

If you’re a frontier worker, your employer will register you for BIS and NISS.

Your unique national number (a.k.a. Belgian tax identification number and NISS) doesn't expire and you never have to renew it.

However, if you’ve been living abroad and decide to switch your place of residency to Belgium, you’ll be given a national registration number instead of BIS.

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