Looking into it again, it appears the residential registration is indeed decentralized, but most of that data seems to still be saved in a central database than

Looking into it again, it appears the residential registration is indeed decentralized, but most of that data seems to still be saved in a central database thanks to Abgabenordnung § 139b [0]. There is something about sharing that information, but I can’t say I understand the legalese ;) [0]: https://www.gesetze-im-internet.de/ao_1977/__139b.html https://www.gesetze-im-internet.de/ao_1977/__139b.html