Belgian National Register Number Generator (NN / NISS)
Generate and format valid Belgian National Numbers (Numéro National / Rijksregisternummer).
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About Belgian National Register Numbers (NN / NISS)
The Numéro National (NN / Rijksregisternummer) is the unified 11-digit civil and social security identifier for citizens and residents in Belgium.
Structured into: birth date (YYMMDD), 3-digit daily counter (odd for males, even for females), and 2 Modulo 97 check digits (with prefix 2 for individuals born from 2000 onwards).
Anatomy & Structure of Belgian National Number
The Belgian NN consists of 11 decimal digits regulated by IBZ:
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 2 | Birth Year | 2 digits | Last two digits of the individual's birth year | 85 |
| 3 to 4 | Birth Month | 2 digits | Month of birth (01 to 12) | 07 |
| 5 to 6 | Birth Day | 2 digits | Day of birth (01 to 31) | 30 |
| 7 to 9 | Counter & Gender | 3 digits | Daily sequence counter (Odd = Male; Even = Female) | 123 |
| 10 to 11 | Check Digits | 2 digits | Modulo 97 check digits (with '2' prefix for births from 2000) | 45 |
NN Calculation & Validation Algorithm (Modulo 97)
NN validation distinguishes centuries through the Modulo 97 prefix rule:
DV = 97 - ((prefix2? + Base9) mod 97)
- 1. Sanitize input by removing dots, slashes, and hyphens.
- 2. Validate that the string consists of exactly 11 numeric digits.
- 3. Test the 20th-century calculation: 97 - (Base9 mod 97) compared against the last 2 digits.
- 4. If it doesn't match, test the 21st-century calculation: 97 - (BigInt('2' + Base9) mod 97).
- 5. If either formula matches the check digits, the number is authentic.