Generate random valid-format Steueridentifikationsnummer numbers for testing
Paste a Steueridentifikationsnummer below to check whether it has a valid format and correct checksum.
The Steueridentifikationsnummer (Steuer-IdNr or IdNr) is an 11-digit permanent tax identification number assigned to every person registered in Germany by the Federal Central Tax Office (Bundeszentralamt für Steuern, BZSt). Introduced in 2008, it remains valid for life and does not change upon marriage, relocation, or name change. It is used for income tax filings, employer payroll reporting (ELSTER), and increasingly as a cross-agency identifier within German federal administration.
A Steuer-IdNr is always exactly 11 digits. The first digit is 1 through 9 — it can never be 0. Among digits 2 through 10, each digit 0 through 9 appears at most twice, and exactly one digit appears exactly twice while no digit appears three times or more. These structural constraints limit the valid number space considerably but are enforced programmatically rather than semantically — the number carries no personal information such as birth date or region.
The 11th digit is computed using the ISO 7064 MOD 11,10 standard: starting with P=10, for each of the first 10 digits compute S = (digit + P) mod 10 (treating S=0 as S=10), then P = (2 × S) mod 11. After processing all 10 digits, the check digit is (11 − P) mod 10. This iterative method detects all single-digit substitution errors and all adjacent transpositions, making it well-suited for long numeric identifiers where data entry errors are common.
ERP systems, payroll software, HR platforms, and tax filing applications serving German businesses must handle Steuer-IdNr correctly. The strict structural rules mean simple random number generation almost always produces invalid IDs, making a purpose-built generator essential for testing. Fake IdNr numbers that pass checksum validation allow developers to test wage statement (Lohnsteuerbescheinigung) workflows, ELSTER API integrations, and database uniqueness constraints safely.
ELSTER (Elektronische Steuererklärung) is Germany's official electronic tax filing system and is mandatory for businesses. The Steuer-IdNr is the key identifier in all ELSTER transactions. Developers integrating with the ELSTER XML interface, building Lohnabrechnung (payroll) software, or connecting to the BZSt's web services need valid IdNr numbers in their test environments. Because the BZSt validates format before processing any API request, structurally correct fake numbers are a prerequisite for successful sandbox testing.