German Tax Number (Steuernummer) Validator
Validate the authenticity, format, and checksum of German Tax Number (Steuernummer).
About German Tax Number (Steuernummer) Validation
The Steuernummer is the administrative tax number assigned by the local Finanzamt for companies, freelancers, and taxpayers.
Format varies by state (Bundesland) with 10 to 11 digits in regional format and 13 digits in the unified ELSTER electronic format.
Anatomy & Structure of Steuernummer
Under the 13-digit unified ELSTER scheme, the German Steuernummer is structured into four regulatory blocks:
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 & 2 | Bundesland | 2 digits | Federal state code (e.g., 09 Bayern, 11 Berlin, 21 Hessen, 32 NRW) | 09 |
| 3 to 5 | Finanzamt | 3 digits | Official tax office district identifier | 123 |
| 6 to 12 | Taxpayer File | 7 digits | Individual taxpayer identification account number | 4567890 |
| 13 | Check Digit | 1 digit | Control digit calculated using weighted Modulo 11 | 5 |
Steuernummer Validation Algorithm (Modulo 11)
The 13th digit of the unified ELSTER format is computed using decreasing weighted sum:
P = (11 - (sum(d_i * w_i) % 11)) % 11
- 1. Extract first 12 digits (Bundesland + Finanzamt + Taxpayer file).
- 2. Apply decreasing positional weights: [13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2].
- 3. Compute modulo 11 of the accumulated weighted sum.
- 4. Subtract remainder from 11. If result is 10 or 11, check digit is 0; otherwise, the remainder value.
- 5. Verify equality with the 13th position.