This Dutch BSN validator checks whether a Burgerservicenummer is
structurally valid using the official 11-proef checksum — the same test used by
Dutch government systems. Type in a number and get an instant pass/fail, with nothing
leaving your browser.
How to use it
Enter the 8 or 9 digit number and click "Check BSN". If it's 8 digits, a leading zero is
assumed automatically, matching how the Dutch tax authority pads short BSNs. The result
tells you immediately whether the number passes the checksum.
How the 11-proef checksum works
Each of the first eight digits is multiplied by a descending weight (9 down to 2), the last
digit is multiplied by -1, and the results are summed. A valid BSN produces a sum that is
exactly divisible by 11. This is the same class of algorithm used to validate IBANs and VAT
numbers — a lightweight way to catch data-entry errors without needing to look anything up
in a database.
Where BSNs are used
Employers, healthcare providers, banks, and the Belastingdienst (Dutch tax office) all use
the BSN to identify individuals across systems. Because it appears on payslips, insurance
documents, and tax forms, a quick client-side sanity check is useful before submitting a
form or importing a spreadsheet of numbers.
Frequently asked questions
What is a BSN?
A BSN (Burgerservicenummer) is the Dutch citizen service number: a unique 8- or 9-digit identifier the Dutch government assigns to every person registered in the Netherlands, used for tax, healthcare, employment, and benefits administration.
What is the 11-proef?
The 11-proef ("eleven test") is the checksum formula built into every valid BSN. It multiplies each digit by a fixed weight, sums the results, and requires the total to be evenly divisible by 11. It catches typos and transposed digits, but it cannot confirm a number was actually issued to a real person.
Does this tool store or send my BSN anywhere?
No. The checksum is computed entirely in your browser with JavaScript. Nothing you type is sent to a server, logged, or stored — you can even disconnect from the internet after the page loads and it will still work.
Can a number pass the 11-proef but still not be a real BSN?
Yes. The 11-proef only checks mathematical structure. It cannot tell you whether a number was ever actually issued, is currently active, or belongs to a specific person. For that, you need an official BSN lookup via a government API, which requires authorization.
What does it mean if my BSN fails the check?
Either a digit was mistyped, the number has too few or too many digits, or it is not a genuine BSN. Double-check the source document and re-enter it carefully — a single transposed digit is the most common cause.