Tax Number in Belgium: An Expats Guide

Stepping into Belgium, the land of divine chocolates and intricate lace, brings its own set of adventures—and yes, that includes the thrilling world of tax numbers!

Fear not, dear expat, for we’re here to decode the mysteries of obtaining your very own Belgian tax number. It’s the golden ticket to navigating the financial landscapes of this charming country. Ready to dive in? Let’s get you set up faster than you can say “praline”.

Let’s dive in!

What Is The Tax Identification Number in Belgium?

The Belgian national number (numéro de registre national/rijksregisternummer) is a unique collection of digits used by Belgian cities to identify individuals registered in their population and foreigner’s registers.

It is used to obtain administrative information such as a person’s residence, civil status, and nationality.

Your Belgian national number (NN) is your Belgian tax identification number, registration number, and social security identification number (NISS/INSZ) – all in one.

Why Do I Need My Belgian National Identification Number?

Anyone wishing to stay in Belgium for more than 90 days will need a Belgian national number.

  • You’ll need your Belgian national number to:
  • Work in Belgium.
  • Set up a business and pay taxes in Belgium.
  • Obtain health insurance, open a Belgian bank account, and make significant purchases, such as real estate or a car.
  • Obtain a Belgian driving license.
  • Set up utilities
  • Register for social security and enjoy online e-government services.

In other words, you must have your Belgian national number to engage in any activity involving the Belgian government.

What’s The Difference Between The National Registry Number And The BIS?

Your Belgian ID may differ based on your residence status:

  • Every Belgian resident is granted a national registration number.
  • Foreign nationals who work but do not live in Belgium (border workers) and foreign employees who remain in Belgium for less than three months are assigned a BIS number.

A National Register Number, commonly known as the national number, is assigned to all Belgian residents and appears on Belgian nationals’ passports or ID cards. Residents might find it on their residence cards or paperwork.

Non-national BIS numbers (numéro Bis/bis-nummer/BIS-Nummer) are provided to individuals who are not required to register in Belgium’s National Register, such as foreign nationals working or living in the country for less than three months.

Similarly, businesses in Belgium must obtain a unique business number. This 10-digit number is assigned during registration at the Crossroads Bank for Enterprises (Kruispuntbank van Ondernemingen) and acts as a VAT number in Belgium.

Why Is It Necessary To Have A Tax Number In Belgium?

In Belgium, having a tax identification number, which is closely tied to the National Register Number, is essential for various administrative and legal purposes. Here are some key reasons why someone needs a tax number in Belgium:

  1. Identification: The tax number, also known as the National Register Number, serves as a unique identifier for every individual residing in Belgium.

It is used for identification in various administrative processes, including taxation.

2. Employment: When you start working in Belgium, your employer will use your tax number to register and report your income to the tax authorities.

It is a crucial element in the employment and payroll processes.

3. Taxation: Your tax number is essential for filing your annual tax return. It is used by the Belgian tax authorities to track your income, assess your tax liability, and determine any tax refunds or obligations.

4. Social Security Contributions: The tax number is linked to your social security contributions. It is used to ensure that you are correctly registered for social security benefits, including healthcare.

5. Residency Status: The tax number is a key factor in determining your residency status for tax purposes. If you reside in Belgium for more than 183 days in a calendar year, you are considered a tax resident.

6. Access to Services: Your tax number is used by various service providers and government agencies to grant you access to essential services, including healthcare, education, and social benefits.

7. Financial Transactions: When engaging in financial transactions, such as opening a bank account or signing a lease agreement, your tax number may be required for identification and verification purposes.

8. Double Taxation Treaties: If you are an expatriate or have income from abroad, your tax number is essential for availing benefits under double taxation treaties that Belgium has with other countries. 

9. Legal Compliance: Having a tax number ensures that you comply with Belgian tax laws and regulations. Non-compliance can lead to penalties and legal consequences.

10. Record-Keeping and Auditing: The tax number is used to maintain a record of your financial activities and to facilitate auditing processes by the tax authorities.

Where Can I Find My Belgian National Identification Number?

Your Belgian national number can be found here:

  • The front of your Belgian ID card
  • The front of your EU card
  • The back of your foreigner’s residency 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

How Can I Obtain A Tax Identification Number In Belgium?

Unlike the fiscal code in Italy and the NIE number in Spain, the tax identification number in Belgium is automatically assigned to all residents upon registration in the national or foreigner’s register.

Belgian nationals obtain their national registration number at birth, whereas foreigners receive it when they register their address with the municipality and apply for a residency permit.

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

You can register at the city office by filling out an online form or sending an email to your municipality.

Normally, you’ll have to submit your

  • Required documents include a valid ID or passport
  • A rental contract
  • EU nationals: proof of income, job contract, or marriage certificate, depending on immigration status.
  • Non-EU citizens: work permit, annex 46, annex 47, or proof of solvency and enrollment certificate for students.

As soon as you register with your local town hall, you will be assigned your NISS social security number and Belgian tax identity number, and you will be considered a resident for tax purposes.

If you are a frontier worker, your employer will register you with BIS and NISS.

How Long Does The Belgian National Number Remain Valid?

Your unique national number (also known as the Belgian tax identification number or NISS) never expires and you never have to renew it.

If you have been living overseas and decide to move to Belgium, you will be assigned a national registration number rather than a BIS number.

How To Apply For A National Number In Belgium?

If you stay in Belgium for more than three months, you must register your address with the municipality. You will then be given your national identification number. 

This number is also automatically included in other documents such as employment and residency permits, as well as marriage certificates. In most circumstances, you do not need to submit separate applications.

If you have not received a residence permit or ID card with a Belgian national number, or if you have misplaced your documentation, contact your local municipality. Your municipal office will most likely be located at the local town hall.

A Belgian national number is free of charge because it is used alongside with other documents.

Step-by-step Guide For Expatriates On The Application Process

1. Register at the Local Town Hall (Commune/Gemeente): As soon as you arrive in Belgium, you must register at the local town hall of the municipality where you will be residing.

Bring your valid passport, visa, and any other required documents. The specific documents may vary depending on your situation and the commune.

2. Receive the National Register Number: Once you have completed the registration process, you will be assigned a National Register Number.

This number serves as your unique identification in Belgium and is used for various administrative purposes, including taxation.

3. Register with Social Security: If you plan to work in Belgium, you will need to register with the Belgian social security system.

This registration is crucial for accessing healthcare and other social benefits.

4. Employment Contract and Tax Status: Your employer will require your National Register Number for employment purposes.

Ensure that your employment contract and tax status are properly established, including the calculation and deduction of taxes from your salary.

5. Tax Residency Determination: Understand the rules for tax residency in Belgium. If you reside in Belgium for more than 183 days in a calendar year, you are considered a tax resident.

6. Tax Return and Filing: As a resident, you are required to file an annual tax return with the Belgian tax authorities.

Use your National Register Number when completing the tax return. You may also need additional documents such as income statements, proof of deductions, and other relevant financial information.

7. Professional Assistance: Given the complexity of tax laws, especially for expatriates, consider seeking assistance from tax consultants or accountants specializing in international taxation.

They can help ensure that you comply with all relevant tax regulations and make the most of any available tax benefits.

8. Online Resources: The Belgian tax authorities provide online resources and forms in multiple languages. Familiarize yourself with these resources to understand your tax obligations.

9. Language Considerations: Be aware of the official languages in Belgium (Dutch, French, and German) and ensure you understand the tax documents and correspondence. Seek translation assistance if needed.

10. Keep Records: Maintain accurate records of your financial transactions, income, and expenses. This documentation will be essential when filing your annual tax return.


There you have it, the end of our journey through the realm of Belgian tax numbers. Armed with this guide, you’re now prepared to tackle the Belgian tax system with the confidence of a local.

Remember, securing your tax number is your first step toward a seamless expat experience in this enchanting country. So, embrace the process, and let it be the start of your Belgian adventure, filled with as much excitement as a box of assorted chocolates.

Happy integrating!

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