Jobinder

Every Dutch company has a Kamer van Koophandel (KvK) number. It is the registration number with the Chamber of Commerce, legally required for any business operating in the Netherlands. The full KvK register is public, free to search, and tells you a surprising amount about a prospective employer in under a minute.

How to look up a KvK number

Go to kvk.nl/zoeken and type either the 8-digit number or the company name. The free result shows you the legal name, trade name(s), registered address, founding date, and the SBI code (the sector classification, similar to NACE / NAICS).

For a few euros, the same register sells extracts (uittreksels) with more detail: directors, authorized signatories, registered capital, and historic name changes. For a job interview you rarely need the paid version; the free search is usually enough.

What to look at — in 10 seconds

Founding date. A company founded last month is legitimate but new. A company founded in 1962 has 60+ years of trading history. Neither is automatically better; both are signals.
Legal form.BV (besloten vennootschap, private limited) is the default for real employers — it implies registered capital and a structured ownership. Eenmanszaak (sole trader) means you'd be working for an individual, often fine for a small plumbing crew, less so for a 50-person operation.
SBI code matches what they say they do. If the posting is for a plumber and the SBI code points to consulting, something is off.
Trade name vs legal name.Almost always different. That's normal — companies trade under brand names. What is not normal is a company that uses three or four trade names with no obvious connection — sometimes a red flag for staffing arrangements that pass workers between entities.
Registered address.If it's a residential house, fine for a small specialist. If it's a notorious mailbox address (some streets in Amsterdam, Rotterdam, Naarden are known as virtual office hubs), think twice for a permanent contract.

What a KvK number does NOT tell you

The register confirms that the company exists, is registered, and has not been struck off. It does not tell you:

Whether they pay on time.
Whether the working culture is decent.
Whether they actually have the work they're hiring for.
Whether they have outstanding tax debts (this requires a different register).
Whether they're using shell entities to obscure responsibility.

For all of that, you need to talk to people who have worked there recently, read company reviews (Glassdoor in NL is patchy; Indeed reviews are sometimes useful), and trust your read of the people in the interview.

Red flags even a verified KvK number can't hide

Founded under 12 months ago, hiring 10+ people. Possible but suspicious — verify they have funding or a parent company.
Mismatched names.The posting says “XYZ Bouw” but the contract is from “ABC Holding B.V.” and your salary will be paid by “PQR Personeel B.V.” This is the classic uitzendconstructie — staffing structure — where the employer of record is different from the company you actually work for. Sometimes legitimate; often used to dodge CAO obligations.
Recent director changes.A new director appointed a month before you're hired isn't a deal-breaker, but ask about continuity.
Lots of dormant subsidiaries. Common in real estate and infrastructure; less common (and a question mark) in pure trades.

The five-minute background check

Before signing a contract, do this:

Look up the legal employer's KvK number — confirm name, address, legal form, age.
Search the trade name on Google with “reviews”, “ervaringen” (experiences), “klachten” (complaints). Read the first 10 results.
Search the director's name on LinkedIn. Are they a real person with a real career history?
Search for the company on faillissementen.com (Dutch bankruptcy register). Anything recent is a hard no.
If the company is in construction, check Bouwend Nederland membership. Members are CAO signatories with formal obligations.

Five minutes of due diligence saves a six-month bad contract. Make it a habit.