What is the Steuernummer?

A definition of the term "Steuernummer", in plain English.

The tax number (Steuernummer) is a unique number that identifies businesses and freelancers. It's a 10 or 11 digit number, and has the format "12/345/67890". It's sometimes written in the unified federal format as "3012034567890", where the first two digits are the number of your Bundesland1, 2.

You obtain this number when you submit the Fragebogen zur steuerlichen Erfassung to the tax office (Finanzamt). Do not confuse the Steuernummer with the tax ID (Steueridentifikationsnummer) or VAT number (Umsatzsteuernummer).

Your Steuernummer is not private. It should appear on your invoices, and in your Impressum.

For more details, see this guide.