Before signing a rental agreement, you will need:
Identity card
Self-disclosure with personal details
Proof of income:
For employees: employment contract and 3 current proofs of income
For self-employed: last tax declaration
For pensioners: Current pension information
Rental debt certificate from the previous landlord
Written confirmation for SCHUFA* request
* What is SCHUFA? – this is where you get information about your credit score in Germany. The landlords or companies can track all bills or fines over time and they basically are rating your ability to pay bills.