Short Answer
Changing your address within Germany requires a new registration process called Ummeldung.
Your official record does not update automatically when you sign a new lease.
What Most Expats Don't Realize
You moved across the city and assumed updating your address online with your bank was enough. Because your name was not physically printed on the new apartment's mailbox, the postal service returned your official tax ID and health insurance letters to the sender. Your health insurance premium was automatically adjusted to the maximum default rate, costing you an unexpected €900.
What To Do
- Print your last name on a clear label and stick it onto your physical mailbox the day you move in.
- Book an Ummeldung appointment at your new local Bürgeramt within two weeks of your move.
- "Ich bin umgezogen und möchte meine Adresse ändern." (I have moved and would like to change my address.) — present this request along with your new landlord's confirmation.
The Truth
Germany relies entirely on physical mail for legal and official notifications. The system assumes that if a letter cannot be physically delivered to a named mailbox, the recipient no longer legally resides there.