The short answer
A KVK number (KVK-nummer) is the eight-digit number every business and organisation gets when it registers in the Dutch Business Register (Handelsregister). Each location also gets a twelve-digit vestigingsnummer. Legal entities and partnerships get a third number, the RSIN, which the Tax Administration builds their VAT number on: NL, the nine RSIN digits, the letter B and two digits. Sole traders have no RSIN; since 1 January 2020 their VAT ID is NL, nine digits, B and two digits, and never contains their citizen service number (BSN). To find a KVK number, search the name, address or postcode and house number on kvk.nl. The search is free and shows up to 50 results, each with KVK number, legal form, vestigingsnummer and address. The number must appear on letters, quotes, invoices, the website and business emails.
The rules below come from kvk.nl, the KVK Developer Portal, belastingdienst.nl and ondernemersplein.overheid.nl, read on 1 October 2026.
The numbers at a glance
Number | Format | Who has one | Used for |
|---|---|---|---|
KVK-nummer | 8 digits | Every registered business or organisation, one per business | Identifying the business; must be on invoices and the website |
Vestigingsnummer | 12 digits | Every registered location | Identifying one place of business |
RSIN | 9 digits | Legal entities (BV, NV, association, foundation, cooperative) and partnerships; not sole traders | Exchanging data with government bodies such as the Tax Administration |
VAT ID (btw-id) | NL + 9 digits + B + 2 digits | Every VAT-registered business | Invoices, letterhead and website |
VAT tax number (ob-nummer) | 9 digits + B + 2 digits | Every VAT-registered business | Contact with the Tax Administration only |
The KVK number
KVK puts it simply: every business or organisation has only one KVK number, even when it runs several activities or trades under several names.
It is permanent in most changes, but not all. The number stays the same when an NV is converted into a BV and when the shares of a BV or NV pass to a new owner. A business gets a different KVK number when the whole business passes to another person, partnership or company. Converting a sole trader's business (eenmanszaak) into a BV or NV also produces a new KVK number and a new VAT ID.
The vestigingsnummer
Every location of a registered business has a twelve-digit vestigingsnummer: a shop, office, workshop or factory. It does not resemble the KVK number of its business. Many associations, foundations and owners' associations have no location and therefore no vestigingsnummer. When a location is taken over and registered as a location of the new owner, it keeps its vestigingsnummer. You are not required to show it on letterhead, invoices or the website.
RSIN and the VAT number
The RSIN (Rechtspersonen en Samenwerkingsverbanden Informatienummer) is issued at registration to legal entities and partnerships, next to the KVK number. For registrations before 2010 it was called the fiscal number (Fi-nummer). Sole traders do not get one, because they already have a BSN. The Tax Administration receives the registration from KVK and uses the RSIN to create other numbers, such as the VAT and payroll tax numbers.
That is why the Dutch VAT number is not the KVK number. For legal forms other than the sole trader, the VAT ID is NL, the RSIN, B and two digits, and the VAT tax number (ob-nummer) is the RSIN, B and two digits. For sole traders the two differ: the ob-nummer contains the BSN, the VAT ID does not. The BSN was removed from sole traders' VAT IDs from 1 January 2020, for privacy. The VAT ID goes on letterhead, invoices and the website; the ob-nummer is only for contact with the Tax Administration.
There is no public list of Dutch VAT numbers, and neither KVK nor the Tax Administration gives out someone else's. Ask the customer or take it from their website, quote or invoice, then validate it in VIES. How to check an EU VAT number explains what a valid result does and does not prove.
Where the KVK number must appear
Under the Business Register Act, KVK says the KVK number must be on letters, quotes, invoices, the website and business emails. Associations without a business, owners' associations, government bodies and religious organisations are exempt. So check the invoice footer, email signature or website before you search.
How to look up a KVK number for free
Open the search on kvk.nl. It is free and needs no account.
Search by what you have. The search accepts names, address details, KVK and vestigingsnummers, the RSIN and the activity description. Postcode and house number is the fastest route for a common name.
Read the result line. Each result shows the KVK number, the legal form, the vestigingsnummer, an address in most cases, whether it is a main location, a secondary location or a legal entity, and whether it is registered or deregistered.
Narrow the search if needed. A search shows at most 50 results. KVK itself points to its API for larger sets.
Several things are not in the free result. Phone numbers, BSNs and the home addresses of directors are not public data at all, and sole traders may shield their business address. The RSIN of another business, and in most cases its directors and signing authority, are in the paid extract; see what a KVK extract shows and costs. Business owners can view company data in the KVK Bedrijvencheck 30 times a year per organisation for free; since early June 2025, KVK no longer sends Business Register data free of charge to private individuals.
The KVK API
For lookups in software, the KVK Developer Portal offers four APIs. Access requires a subscription of 6.40 euros per month; the KVK APIs are exempt from VAT, so invoices carry no VAT.
API | What it does | Price per call |
|---|---|---|
Zoeken | Finds the KVK number by name, address, KVK number, RSIN or vestigingsnummer; up to 100 results per page | €0 |
Basisprofiel | Basic data per KVK number: names, trade names, registration date, SBI codes, addresses, websites | €0.02 |
Vestigingsprofiel | Data per location, by vestigingsnummer | €0.02 |
Naamgeving | Trade names of a registration | €0.02 |
Source: developers.kvk.nl/nl/pricing. A change service (Mutatieservice) costs 1,279 euros per year on top of an API subscription, and a test environment is available. The free open dataset Basis Bedrijfsgegevens is no shortcut: it covers only BVs and NVs and leaves out the KVK number, the name and the full postcode. The activity codes in the Basisprofiel are explained in SBI codes in the Netherlands.
KVK number and Belgian enterprise number compared
Netherlands | Belgium | |
|---|---|---|
Company number | KVK-nummer, 8 digits | Enterprise number, 10 digits, starting with 0 or 1 |
Location number | Vestigingsnummer, 12 digits | Establishment unit number, 10 digits, starting with 2 to 8 |
VAT number | Built on the RSIN (or a separate number for sole traders), not on the KVK number | BE followed by the enterprise number itself |
Sole traders | KVK number, no RSIN | Enterprise number |
Free lookup | kvk.nl search, up to 50 results | KBO Public Search, no account needed |
The practical difference: in Belgium one number is both the company ID and, with BE in front, the VAT number. In the Netherlands you need two separate fields, and you cannot calculate the VAT ID from the KVK number. The Belgian enterprise number covers its format, the modulo 97 check and the lookup.
Using the KVK number as a key
Match Dutch companies on the KVK number, not the name. Store it as eight-digit text in its own field, with the vestigingsnummer and VAT ID in separate fields, and re-check a customer after an incorporation or takeover, since both can produce a new number.
If you have a file of Dutch companies to complete, Bizzy covers Dutch companies through Creditsafe data and can enrich a CSV that has the KVK number as an eight-digit column, matching each row on that number instead of on a name. To compare the other sources of Dutch company data, see the best B2B databases for the Netherlands.
Frequently asked questions
How do I look up a KVK number? Search the company name, address or postcode and house number on kvk.nl. It is free. The number is also printed on the company's invoices, website and business emails.
How many digits does a KVK number have? Eight. A vestigingsnummer has twelve, an RSIN nine.
Is the KVK number the same as the VAT number? No. For a BV, NV or other legal entity, the VAT ID is NL, the RSIN, B and two digits. A sole trader's VAT ID is a separate number that has not contained the BSN since 1 January 2020.
Does a company keep its KVK number forever? Mostly. It stays when an NV becomes a BV or shares change hands, but a business gets a new KVK number when the whole business passes to another owner, or when a sole trader converts to a BV or NV.
Photo: the Magere Brug in Amsterdam, C messier, CC BY-SA 4.0, via Wikimedia Commons