Home National Register Number Belgium
Belgium National Register Number validator
How the National Register Number format works
- Format
- 11 digits
- Example
- 85011512355
Things to watch for
- 11 digits: the first 6 encode date of birth (YYMMDD), the next 3 are a daily serial, and the last 2 are a mod-97 check
- Because the birth year is only two digits, this tool accepts a number if either the pre-2000 or the 2000-and-later check formula matches — the century isn't recoverable from the digits alone
- Checksum only — validation happens entirely in your browser and nothing you enter is stored; a passing check doesn't confirm the number is currently assigned
^[0-9]{11}$The National Register Number (Rijksregisternummer in Dutch, Numéro de Registre National in French) is the 11-digit identifier Belgium assigns to every resident — citizens and registered foreign nationals alike — for tax returns, health insurance, employment contracts, and virtually any interaction with a public body. It’s printed on the eID card and requested on almost any official form.
Structurally, it’s built from real information rather than being an arbitrary serial: the first 6 digits are the date of birth (YYMMDD), the next 3 are a sequence number assigned within that day’s registrations, and the last 2 digits are a checksum computed from the first 9 using a mod-97 calculation. Because only two digits carry the birth year, the number by itself can’t distinguish, say, 1901 from 2001 — so the official formula is effectively run twice, once assuming a birth year before 2000 and once assuming 2000 or later, and a number is treated as valid if either version’s arithmetic matches.
How this validator works
This tool confirms the input is 11 digits, then reruns both versions of the mod-97 calculation (pre-2000 and post-2000) against the first 9 digits and compares each result to the final 2 — accepting the number if either matches. Everything runs client-side in your browser; nothing is transmitted or stored.
What a pass doesn’t tell you
A pass confirms the 11 digits are mathematically self-consistent under one of the two valid formulas — it doesn’t confirm the number was ever assigned to a real person or is currently active in the National Register. Only Belgium’s population registry can confirm that.
Scope: this page covers National Register Number format and mod-97 checksum validation only — not identity or residency verification. Because the number encodes a date of birth, treat a pass strictly as a typo-check, not as information about the person behind it.
Content last reviewed 2026-07-23.
National Register Number FAQ
What does a Belgian National Register Number encode?
The first 6 digits are a date of birth in YYMMDD order, the next 3 are a serial number assigned among that day's registrations, and the final 2 digits are a mod-97 check calculated from the first 9.
Why does this tool try two different formulas?
Because the birth year is only two digits, the number alone can't say whether someone was born in 1985 or 2085. The official check calculation is applied differently depending on the assumed century, so this tool accepts a number if either version of the formula produces the two check digits given.
Is it safe to test a real National Register Number here?
Yes. Validation happens entirely in your browser using JavaScript — the number you enter, including the birth date it encodes, is never transmitted to a server, logged, or stored. A pass only confirms the digits are arithmetically consistent; it doesn't confirm the number is currently assigned by the National Register.