Short Answer
Your personal Steuer-ID stays with you for life, but your Steuernummer changes every time you move to an area under a different tax office. Freelancers must proactively update their records with the local authorities after changing cities.
What Most Expats Don't Realize
You moved from Munich to Berlin and kept sending your freelance invoices using the exact same tax numbers you had used for years. The local tax office in your new city did not receive your registration, flagged your active invoices as unregistered commercial activity, and froze your business bank account. You lost 1,200 € in delayed client payments and administrative fees while trying to untangle the bureaucratic mistake.
What To Do
- Bring your new registration certificate (Anmeldebestätigung) to the local tax office (Finanzamt) in your new city.
- File a formal change of address notification through the online ELSTER portal immediately after your move.
- "Ich bin umgezogen und beantrage eine neue Steuernummer für meine freiberufliche Tätigkeit." (I have moved and am applying for a new tax number for my freelance activity.) — email this request to your new local tax office.
The Truth
The Steuer-ID is a modern federal project; the Steuernummer is a remnant of the era when tax offices were independent kingdoms.