Rental Agreement and Confirmation of the Housing Provider
When you enter into a rental agreement, you must receive your own original hardcopy signed by the landlord or rental company.
For the official registration of your home address (for a stay in Germany of three months or longer), you also need a Confirmation of the Housing Provider for presentation to the Registration Office (in German: 'Wohnungsgeberbestätigung zur Vorlage bei der Meldebehörde'). This is an official form of the Freistaat Sachsen (Free State of Saxony).
It must be filled in by your landlord. You will need it to register at the Citizen's Office (Bürgerbüro).