Ondernemingsnummer on Your Belgian Website: Is It Required?

If you run a business in Belgium, you are legally required to display your ondernemingsnummer on your website. Many business owners do not know this, and many web designers skip it.

Here is what the law says and how to comply.

What the law requires

Under Belgian law, specifically WER Boek XII Art. XII.6 (Wetboek van economisch recht, Book XII on information society services), every business that provides services through a website must display the following information:

• Ondernemingsnummer (KBO/BCE registration number, 10 digits starting with 0 or 1)
• Legal name of the business (as registered with the KBO)
• Registered office address (maatschappelijke zetel)
• Email address where you can be contacted directly

If you are a BV (besloten vennootschap) or NV (naamloze vennootschap), you also need to display details about your company form and share capital where applicable.

This applies to your website, your emails, your invoices and any other business communications.

The specific legal basis

The requirement comes from WER Boek XII Art. XII.6, which transposes the EU E-Commerce Directive (2000/31/EC) into Belgian law. This article states that every provider of an information society service must make certain identification details permanently, easily and directly accessible to users and to competent authorities.

WER Boek III (company law provisions) covers the duty to register with the Kruispuntbank van Ondernemingen (KBO) in the first place. Every Belgian business entity must register before starting its activities. The registration creates the ondernemingsnummer. Art. XII.6 then requires you to display it.

WER Boek XV covers enforcement and sanctions. Failing to comply with the identification obligations can lead to administrative fines imposed by the FOD Economie's Economic Inspection (Algemene Directie Economische Inspectie). For legal persons, these fines follow the tiered system in Boek XV, with ceilings that depend on the severity of the violation.

For companies (BV, NV, CV), WER Boek III Art. III.74 adds that the company form, the word "rechtspersoon" if applicable and the company name must appear on all documents going out from the company. Electronic documents including websites are covered.

Where to put it

The most common and practical location is your website's footer. Put it on every page by adding it to your footer template.

Good examples:

• "BE0123.456.789 | Brussels"
• "Bakkerij De Molen BV | BE0123.456.789 | Maatschappelijke zetel: Brusselstraat 1, 1000 Brussel"

Some businesses also include it on their contact page, about page or impressum page. The footer is the minimum. If you have a dedicated legal or contact page, include it there too.

BTW number too?

In Belgium, your BTW-nummer is your ondernemingsnummer prefixed with "BE". So if your ondernemingsnummer is 0123.456.789, your BTW-nummer is BE0123.456.789.

This is different from the Netherlands, where the BTW-ID is a separate number. In Belgium, displaying your ondernemingsnummer effectively gives people your BTW number too. Still, it is good practice to label it explicitly, especially on invoices and in your website footer.

Format: BE0123.456.789

Read the full details in our Belgian VAT number display guide.

What happens if you do not comply

FOD Economie's Economic Inspection can investigate non-compliance with Art. XII.6. In practice, enforcement often follows complaints, but the risk increases when:

• A customer files a complaint with FOD Economie
• You are involved in a legal dispute
• A competitor reports you
• The Economic Inspection runs a sector scan on your industry

Beyond fines, not displaying your ondernemingsnummer can make your business look less trustworthy. Belgian consumers and business partners expect to see it. They can verify it at kbopub.economie.fgov.be within seconds.

How enforcement typically works

The Economic Inspection under FOD Economie handles enforcement of business identification obligations.

The warning phase. The Economic Inspection usually starts with a written warning asking you to add the required information to your website within a set period, typically four to six weeks. Most cases end here. You add the number, and that is it.

The fine phase. If you ignore the warning, an administrative fine can be imposed under Boek XV WER. The amount depends on the seriousness of the violation and the size of the business. For a small business that forgot to add its number, fines tend to be modest. For a larger company that deliberately hides its identity, fines escalate.

Repeat offenders. Businesses that have been warned before and still do not comply face escalating penalties. The Economic Inspection keeps records of previous enforcement actions, and repeat violations are treated more seriously.

Complaints drive enforcement. The Economic Inspection does not have the resources to check every website in Belgium. Most enforcement actions start with a complaint from a customer, a competitor or another government agency. If someone reports that your website does not display your ondernemingsnummer, that is when they take notice.

Legal disputes as trigger. Courts also look at this. If you end up in a commercial dispute and your website does not display the required business information, the other party's lawyer will bring it up. It creates an impression of untrustworthiness, and judges notice.

E-commerce extra requirements

If you sell products or services online, additional rules apply beyond just the ondernemingsnummer. These come from the EU Consumer Rights Directive (2011/83/EU), which is implemented in Belgian law under WER Boek VI (market practices and consumer protection).

The directive requires that consumers can identify who they are buying from before they place an order. This means:

• Your full name and geographic address must be easily accessible (not hidden behind a contact form)
• An email address where customers can reach you
• Prices must clearly state whether they include BTW
• Delivery costs and estimated delivery times must be shown before checkout
• Your return policy (14-day withdrawal right under WER Boek VI Art. VI.47) must be clearly stated

The Consumer Rights Directive also requires that your order button clearly indicates a payment obligation. A plain "Submit" button is not legal. It must say something like "Bestelling met betalingsverplichting" or "Order and pay." See our order button requirements guide for the full breakdown under WER Boek VI Art. VI.45.

If you run a Belgian webshop, the ondernemingsnummer is just one item on a longer compliance checklist. Your terms and conditions need to be in order too.

What about foreign businesses selling in Belgium?

If your business is registered outside Belgium but you sell to Belgian customers, the Belgian KBO requirement does not apply to you directly. You do not need a Belgian ondernemingsnummer just because Belgian consumers visit your website.

However, you still need to identify yourself. Under the EU E-Commerce Directive (2000/31/EC), every business selling online must display equivalent business identification from their own country. For a German business, that means Handelsregister details. For a Dutch business, their KvK number. For a UK business post-Brexit, their Companies House number.

If a foreign business establishes a permanent presence in Belgium, such as opening a Belgian branch office, warehouse or physical store, they do need to register with the KBO. That branch gets its own ondernemingsnummer, and the display requirements apply.

The short version: you do not need a Belgian ondernemingsnummer to sell to Belgium from abroad, but you do need to display your own country's equivalent business registration.

Multi-location businesses and the vestigingseenheidsnummer

Businesses with more than one location in Belgium have both an ondernemingsnummer and one or more vestigingseenheidsnummers (establishment unit numbers).

The ondernemingsnummer (10 digits, starting with 0 or 1) identifies your legal entity. There is one per business. The vestigingseenheidsnummer (10 digits, starting with 2) identifies each physical location where your business operates. Every registered business has at least one vestigingseenheidsnummer, even if they only have a single location.

For your website, the ondernemingsnummer is the one you must display. You do not need to list vestigingseenheidsnummers on your site unless you want to help customers identify a specific branch.

If you run a chain of restaurants, a retail franchise or a consultancy with multiple offices, keep the main ondernemingsnummer in your website footer. If you have individual location pages, you can optionally add the vestigingseenheidsnummer for that location.

You can look up any ondernemingsnummer or vestigingseenheidsnummer at kbopub.economie.fgov.be. Each listing shows the address, trading name and activities registered for that entity.

What if I am a sole trader (eenmanszaak)?

Self-employed professionals and sole traders in Belgium are registered with the KBO and have the same obligation. Your ondernemingsnummer must appear on your website.

Some sole traders worry about displaying their home address. In Belgium, you can register a maatschappelijke zetel at a different address from where you live if you have a separate office or use a business centre. Virtual office services are available across Belgium, typically starting at around EUR 25 to EUR 75 per month.

One thing Belgian sole traders often miss: your KBO registration also includes a description of your business activities (NACE codes). If your activities have changed since you registered, update them through the KBO. Certain activity changes may require an update through an enterprise counter (ondernemingsloket).

Quick fix

1. Find your ondernemingsnummer at kbopub.economie.fgov.be
2. Add it to your website footer with your business name and registered office city
3. Prefix it with "BE" if you also want it to serve as your BTW number display
4. Make sure this information appears on every page

Total time: about 10 minutes. While you are checking your business details, also make sure you are displaying the right VAT number format. If you run a webshop, your checkout page has its own requirements under WER Boek VI too.

Frequently asked questions

Do I need a separate impressum page?

In Belgium, there is no strict requirement for a separate impressum page like in Germany. But it is good practice to have an "About" or "Contact" page with all your business details. At minimum, put your ondernemingsnummer in the footer. If you also serve German or Austrian customers, check our guide on Impressum requirements across Europe.

My web designer built my site. Why did they not add my ondernemingsnummer?

Most web designers focus on design and functionality. Legal requirements like business identification numbers are usually the responsibility of the business owner. Now you know, so you can add it or ask your designer to do it.

Is a 10-digit number always an ondernemingsnummer?

Belgian ondernemingsnummers are 10 digits and always start with 0 or 1. They are usually formatted with dots: 0123.456.789. Vestigingseenheidsnummers are also 10 digits but start with 2. You can verify any number at kbopub.economie.fgov.be.

Can I display my ondernemingsnummer as an image instead of text?

Technically, the law does not specify the format. But using an image is a bad idea for two reasons. First, search engines cannot read text in images, so you lose any SEO benefit from having your business details visible. Second, screen readers used by visually impaired visitors cannot read image text either, which creates an accessibility barrier. Use plain HTML text.

What if my KBO registration is pending?

If you have started the registration process but have not received your ondernemingsnummer yet, you should not be trading. Under Belgian law, you must complete your KBO registration before you begin business activities. Once you have your number, add it to your website immediately.

I have a VZW (non-profit). Does this apply to me?

Yes. VZWs (verenigingen zonder winstoogmerk) and IVZWs (internationale verenigingen zonder winstoogmerk) that are registered with the KBO have the same identification obligations as commercial businesses. If your VZW has a website, your ondernemingsnummer belongs in the footer.

Run a free scan of your website to check whether your ondernemingsnummer, BTW details and other legal information are properly displayed. The scan covers legal, privacy, security and accessibility in under a minute.