German Tax ID (Steuer-IdNr) Generator
Generate and format valid German Tax ID (Steuer-IdNr) for software testing and development.
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About German Tax ID (Steuer-IdNr)
The German Tax ID (Steueridentifikationsnummer or Steuer-ID) is the unique, permanent 11-digit fiscal identifier assigned to every resident in Germany.
Consists of 11 numerical digits, where the first digit is non-zero and the 11th digit is a checksum computed according to ISO 7064 Modulo 11, 10 (DIN 5007-1).
Anatomy & Structure of German IdNr
The Steuerliche Identifikationsnummer (IdNr) consists of exactly 11 numeric digits with protected pseudo-random distribution.
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 10 | Base Number | 10 digits | Sequential base where first digit is never 0 and exactly one digit appears twice | 1234567890 |
| 11 | Check Digit | 1 digit | Control digit calculated according to ISO/IEC 7064, Mod 11, 10 standard | 4 |
IdNr Validation Algorithm (ISO/IEC 7064, Mod 11, 10)
The official BZSt algorithm applies iterative modular sum and product according to ISO/IEC 7064 standard:
P = ((S * 2) % 11) | S = (d_i + P) % 10
- 1. Initialize accumulated product variable with base value P = 10.
- 2. For each of the first 10 digits: compute sum S = (digit + P) % 10. If S is 0, reset S = 10.
- 3. Update product: P = (S * 2) % 11.
- 4. Compute check digit candidate: C = 11 - P. If C is 10, check digit is 0; otherwise, it equals C.
- 5. Compare with the 11th digit to ensure mathematical validity.