Belgian national register number
Belgium · Individuals
Paste or type the number — punctuation is optional.
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What this check does — and what it cannot do
This tool checks the number's structure and its check digit, using the published algorithm for that document. A number that passes is well formed: it is arithmetically consistent and could have been issued.
It cannot tell you whether the number was actually issued, whether it is active, or who it belongs to. Only the issuing tax authority can confirm that, through its own lookup service. Treat a passing result as "worth submitting", never as proof of identity.
How the Rijksregisternummer check works, and what the number tells you
A Rijksregisternummer is a personal identity number issued in Belgium. This page checks one against the published rule, shows which specific test it fails when it fails, and decodes the facts the digits carry. Everything runs in your browser — the number you type is never sent anywhere.
How it works
- Applies the published checksum rather than only checking the length and shape.
- Names the exact rule that failed, so a typo is distinguishable from a number that was never valid.
- Decodes what the number encodes: date of birth, sex.
- Does not generate numbers. This one identifies a person, and a page that manufactures plausible identity numbers is a liability rather than a feature.
11 digits: YY MM DD SSS CC SSS sequence, odd for men and even for women CC check CC = 97 - (the first nine digits, as a number, mod 97) for people born from 2000, prefix a 2 before taking the mod
Worked example
Checking 85073003328, a valid Rijksregisternummer, digit by digit.
- input 85073003328
- normalised 85.07.30-033.28
- Date of birth 1985-07-30
- Sex Male
- Checksum Mod 97
- result passes every published check
The checksum passes, so the number is internally consistent, and the tool reads off date of birth, sex. Internal consistency is not the same as the number being issued to somebody — see the note below.
Reading the result
- The 2000 rule means a number can be checked two ways, and both are legitimate — which is exactly why a naive implementation rejects everyone born this century. Month 00 is also valid: it is used where the date of birth was unknown at registration, so the tool does not treat it as an error.
- A passing checksum means the digits are consistent with each other, not that the number exists. Only Belgium's own registry can tell you whether a number was actually issued and is still valid, and no offline tool can substitute for that.
- The check happens entirely in your browser. Nothing is uploaded, logged, or stored, which matters more here than on most tools because these numbers are personal data in every jurisdiction that issues them.
- Punctuation is ignored. Spaces, dots, dashes and slashes are stripped before the check, so a number pasted in any common local format is read the same way.
Common questions
- My number is real but this says it is not valid. Why?
- Check for a transposed pair of digits first — that is the single most common cause, and every checksum here is designed to catch it. Failing that, the number may predate the current rule: several countries changed or introduced their checksum at a known date, and older numbers were not reissued. If the tool names a specific rule that failed, that is the one to look at.
- Does a valid result mean the number is registered?
- No, and this is the limit worth understanding. A checksum proves the digits are mutually consistent, which catches typos and made-up numbers. It cannot prove the number was issued, is still active, or belongs to the person quoting it. Only the issuing authority's own lookup can do that.