How is a German Steuer-ID validated?

Three rules apply. The first digit must not be zero. Within the first ten digits exactly one digit value repeats (appearing two or three times) while every other value appears at most once. The eleventh digit is an ISO 7064 MOD 11,10 check digit computed over the first ten. This tool implements all three exactly.

Does a valid result mean the Steuer-ID is real?

No. A pass means the number is structurally and mathematically well-formed. It cannot confirm the ID is issued, active or linked to a specific person — only the Bundeszentralamt für Steuern holds that data.

Is my Steuer-ID sent anywhere?

No. Validation is entirely client-side — the number never leaves your browser and there are no network requests.

Germany Steuer-ID Validator (Steuerliche Identifikationsnummer)

Germany Steuer-ID validator

Enter an 11-digit Steuer-ID (Steuerliche Identifikationsnummer / IdNr) and the tool checks all three official rules: the first digit is not zero, the digit-frequency rule holds across the first ten digits, and the eleventh digit is the correct ISO 7064 MOD 11,10 check digit.

Each check is shown individually so you can see exactly why a number passes or fails.

Privacy-first: the Steuer-ID is processed entirely in your browser — nothing is uploaded or sent anywhere. The tool validates the documented format only and does not query any tax-office database.