Buying Dutch company data: eight checks before you order

A company list looks like a simple product: names, addresses, phone numbers. In practice, suppliers differ greatly in where the data comes from, how old it is and what you may legally do with it. With the eight checks below you compare quotations on the same basis.

1. Where does the data come from?

A serious supplier names its sources: open map data, company websites, public registers, its own research. Be careful with lists that “come from the KVK business register” without it being clear how. The Chamber of Commerce (KVK) supplies data under terms of use and passes on the Non-Mailing Indicator; a copy without that flag is a risk for your postal campaign. Read more in our article on the KVK business register.

2. What is the data date?

Company data ages. In 2025 CBS counted 197,365 business start-ups and 174,185 closures (provisional figures). So ask for the date on which the data was collected or checked, and have that date recorded in the quotation. “Updated daily” without explanation is not a data date.

3. How many records have the field you need?

A list of 10,000 companies of which 3,000 have a phone number is, for a calling campaign, a list of 3,000. Ask for the number of records with each mandatory field (phone, website, email) after your filters on industry and region. A total for the whole database says nothing about your selection.

4. Is the legal form included?

In the Netherlands the legal form determines which rules apply. A bv, nv, foundation or association is a legal entity, which you may call on business matters. A sole trader, general partnership (vof), limited partnership (cv) or professional partnership (maatschap) may only be called with prior consent (Article 11.7(2) of the Telecommunications Act). Without a legal form column you cannot make that distinction.

5. How does the supplier handle objections and the Non-Mailing Indicator?

Data of sole traders is usually personal data. The supplier must inform the people concerned (Article 14 GDPR) and process objections (Article 21 GDPR). In addition, businesses can register a Non-Mailing Indicator with the KVK, meaning their address must not be used for advertising mail. Ask how the supplier excludes those cases.

6. Is there a sample file?

A sample file shows the columns, the format of postcodes and phone numbers and the character encoding. That way you see in advance whether the file fits your CRM without detours. A sample with fictitious companies proves nothing about coverage; that is what the count per field (point 3) is for.

7. What does a usable record cost?

8. What may you do with the data?

Read the licence: may you keep the data in your CRM, share it with an agency, reuse it after a year? And know what the list does not settle: it contains no consent for email marketing. Unsolicited commercial email is prohibited towards legal entities as well, unless the recipient gave prior consent or published the address itself for such messages (Article 11.7 Telecommunications Act). More in B2B outreach and the Telecommunications Act.

Warning signs

• “Email addresses with consent” without being able to see who consented to what, and when.
• No sources and no data date, but a large total.
• “Unlimited use for all channels” without any reservation for the Telecommunications Act or the GDPR.
• Personal email addresses and mobile numbers of employees without explanation of their origin.

Under data sources and methodology we explain how we build the Dutch company database. Our database currently relies on one source, the open map data of Overture Maps; every quotation states the actual number of records per field and the data date.