How to vet your contractor in Belgium: the complete checklist.

01Check 1: KBO registration

The Crossroads Bank for Enterprises (KBO) is Belgium's official company database [2]. Every contractor operating legally is in it. This is where you start.

How to search

Go to kbopub.economie.fgov.be [2]. You can search by company number, name or address. If you have a quote, the company number is normally on it. It starts with 0 or 1, followed by nine digits.

What to check

Status. You're looking for "Active" (code AC). "Ceased" (code ST) speaks for itself. A company that isn't active in the KBO can't issue you a valid invoice.

Activity codes. Every company has NACE-BEL activity codes in the KBO. For construction, those are codes starting with 41 (building construction), 42 (civil engineering) and 43 (specialised construction activities) [3].

Check whether the activities match the work your contractor is quoting. A company registered for painting work but sending you a quote for shell construction should raise questions.

Founding date. How long has the company existed? A recent founding isn't automatically suspicious. But combined with an unusually low quote and no references, it's reason for caution.

Watch out: NACE-BEL 2025

Since 1 January 2025, new NACE-BEL codes apply [3]. All existing codes were converted automatically to the new system. But that automatic conversion wasn't always correct, especially where one old code could map to several new ones [3].

So check not just whether construction activities are listed, but whether they're the right ones for the work you're having done.

02Check 2: VAT validation

Why it matters

If you're renovating a home older than ten years, you're in principle entitled to the reduced VAT rate of 6% instead of 21% [7]. But that only applies if your contractor is an active VAT-registered business. An invalid VAT number can cost you that benefit.

Since 2022, the old VAT certificate has been replaced by a standard declaration on the invoice [7]. The contractor states on every invoice that the conditions for 6% VAT are met. But if the VAT number itself isn't active, that basis falls away.

How to check

You can validate Belgian VAT numbers via the FPS Finance site [6]. For a Europe-wide check, use the European Commission's VIES tool [6]. Enter the company number (for Belgium: BE + ten digits). You see immediately whether the number is active.

If the number isn't active, ask for an explanation before going further. Never pay an invoice at 6% VAT if you're not sure the VAT number is valid. The difference between 6% and 21% on a 100,000 euro renovation is 15,000 euros.

03Check 3: Tax and social security debts

Checkinhoudingsplicht.be

At checkinhoudingsplicht.be [4], enter your contractor's company number. You see immediately whether there are tax or social security debts.

A nuance. The withholding obligation is technically meant for professional parties, not for private homeowners [4]. As a private individual you're not obliged to withhold part of the invoice if there are debts. But you can still use the tool as an information source. And you should.

What you see

The tool shows two things: tax debts (with FPS Finance) and social security debts (with the NSSO).

"No withholding obligation" is good news. "Withholding obligation applies" means there are outstanding debts. That doesn't necessarily mean your contractor is about to go bankrupt. Sometimes there's a dispute, sometimes an administrative delay. But it's a signal. Especially in combination with other red flags.

Bouwunie checkup tool

A quicker option: the Bouwunie checkup tool at checkup.bouwunie.be [11]. It combines several checks in one step: KBO registration, tax and social debts, and the JustBan list (the list of convicted fraudsters). Handy as a starting point. But for financial health you still need to visit the National Bank.

04Check 4: Financial health

The National Bank's Central Balance Sheet Office

Via the National Bank of Belgium's Central Balance Sheet Office [5] you can consult the annual accounts of every Belgian company. Free, for anyone.

Go to nbb.be, search by company number, and you'll find the annual accounts of the past years [5]. You don't need to be an accountant. Three things are enough.

Three things to check

Equity. This is the difference between what the company owns and what it owes. Positive is normal. Negative means debts exceed assets. That's a serious signal.

Turnover. Look at the trend over two to three years. Stable or growing is fine. A sharp drop can point to less work or lost clients.

Debt ratio. How much debt does the company have compared to equity? Construction companies typically run with a lot of outside capital, that's normal in the sector. But if debts rise while turnover falls, that's a pattern you need to take seriously.

The combination

One weak number isn't necessarily a problem. Maybe there was an exceptional year, a large investment, a restructuring. But falling turnover, rising debts and negative equity together: that's the profile of a company in trouble.

05Check 5: Recognition and professional competence

Contractor recognition

Contractor recognition is an official classification system run by the FPS Economy [8]. It tests technical competence, financial capacity and professional integrity.

For public works, recognition is mandatory (law of 20 March 1991) [8]. For private residential construction it isn't. But if your contractor is recognised, you know the company meets those criteria. You can consult the list of recognised contractors on the FPS Economy website [8].

Professional competence

Since 1 January 2019 the establishment law has been abolished in Flanders [9]. Concretely: in Flanders you no longer need to present proof of professional competence to start a construction business. In Brussels and Wallonia that obligation still applies [9].

That makes the other checks in this article extra relevant if you're building in Flanders. The bar to starting a construction company is lower there, which means not every company has the same experience or knowledge.

06Check 6: Insurance

What your contractor should have

Liability insurance (BA). The minimum. Covers damage the contractor causes to third parties or to your property during the work.

Ten-year liability insurance. Mandatory since 1 July 2018 under the Peeters-Borsus law [10]. Covers serious defects to the finished shell (stability, solidity, water-tightness) for ten years after handover. Applies to work requiring a building permit [10].

All Construction Risks insurance (ABR). Not mandatory, but recommended for larger or more complex projects. Covers damage to the building itself during construction.

How to check this

Ask your contractor for an insurance certificate. That's a document from the insurer confirming that the policy is active and what it covers. A serious contractor sends this without hesitation.

Does your contractor refuse to show a certificate? That should raise questions. The ten-year liability insurance is legally required [10]. A contractor who doesn't have it isn't operating according to the law.

07What if you find something?

One weak point is worth a conversation. Several red flags together are a reason to look elsewhere.

One signal. Ask the question. "I see your company had negative equity last year, can you explain that?" A good contractor gives a clear answer. Maybe there was an exceptional year, an investment in equipment, a change in the corporate structure. Context makes the difference.

Multiple signals. Negative equity, falling turnover, tax debts, recent founding without references. In that combination it's wiser to look for another contractor. Not out of distrust, but out of caution. Want to know what happens if your contractor still goes bankrupt? Read our detailed article about it.

Active tax or social debts. This is the clearest signal. A company that isn't paying its taxes or NSSO contributions usually has cash-flow problems. Look for another contractor.

Having the conversation

You don't need to justify yourself. "I've looked at the KBO and the National Bank and I have a few questions" is a normal sentence. Every serious contractor understands that. It shows you're an informed homeowner.

A contractor who reacts defensively to a business question about financial health? That's a signal in itself.

08All checks in one view

09Why this matters more and more

Over the past few years, bankruptcies in construction have risen every year [1]. At the same time, the bar to starting a construction business in Flanders has dropped since the establishment law was abolished [9]. More companies, fewer required qualifications.

That makes these checks non-optional. Check financial health before you sign, the way you'd check a Car-Pass when buying a used car. A good contractor won't hold it against you. It shows you're a serious homeowner. Once you've picked a contractor, read how to compare quotes correctly so you know exactly what you're signing.