How to Use the Netherlands BSN Checksum Validator
- Type or paste a 9-digit BSN into the box above — dots and spaces are fine, the tool strips them automatically.
- Click Check. The tool verifies the number is 9 digits and passes the official 11-proof (elfproef).
- Read the decode table showing the first 8 digits and the verification digit separately.
- Nothing you type is uploaded anywhere — the whole calculation runs as plain JavaScript in your browser tab.
What the BSN Is
The Burgerservicenummer (BSN) is the Dutch equivalent of a social security number — a 9-digit identifier used across Dutch government services, healthcare, taxation, and employment. Like Germany's Steuer-ID, it's an administrative number that encodes no personal information (no birth date, no region): it's simply a unique identifier subject to a specific checksum rule.
The Checksum: 11-Proof (Elfproef)
The "elfproef" (literally "eleven-test") is a weighted checksum used across several Dutch identification numbers, including the BSN, the RSIN (used for organizations), and traditionally Dutch bank account numbers. Each of the 9 digits is multiplied by a fixed weight — 9, 8, 7, 6, 5, 4, 3, 2 for the first eight digits, and −1 for the ninth — and the resulting sum must be exactly divisible by 11.
This single rule is elegant precisely because it's symmetric: the same weighted-sum formula both generates valid numbers and checks them, and it reliably catches the two most common data-entry mistakes — a single mistyped digit, and two adjacent digits swapped.
Worked Example
111222333What This Tool Does NOT Do
This checks the 9-digit format and the 11-proof checksum only. It does not query the Rijksdienst voor Identiteitsgegevens (RvIG) or any other Dutch government system, and cannot confirm a BSN is actually issued, active, or belongs to a real person. Because the BSN carries no embedded personal data, there's nothing else to decode beyond the digits and the verification math — unlike, say, Italy's Codice Fiscale, a passing BSN check tells you nothing about who the number might belong to.
Common Mistakes
- Assuming the BSN encodes a birth date the way Italy's or France's identifiers do — it deliberately doesn't
- Forgetting the ninth digit carries a negative weight (−1) rather than a positive one when checking by hand
- Confusing the BSN's elfproef with a completely different checksum family (like Luhn, used for GSTIN) — they are not interchangeable
- Treating a checksum pass as proof the BSN is currently active — this tool has no way to know that
Frequently Asked Questions
Is my BSN uploaded anywhere? No — everything runs locally in your browser tab.
Does the BSN encode my birth date or gender? No — unlike Italy's Codice Fiscale or France's NIR, the BSN is a plain administrative number with no embedded personal data.
Does a valid 11-proof mean the BSN is real? No — it means the number is internally consistent, not that it's actually issued.
Is this tool free? Yes, completely free, with no login and no usage limit.