A lease agreement (Mietvertrag) governs all the important terms and conditions for the rental of a house or apartment. For example, it defines the amount of your base rent, the ancillary expenses that are payable, and the duration of the lease. Read the lease agreement carefully and, before signing it, clarify any matters that may need resolution. As a general rule, you should aim to have your monthly rent not be more than 30 percent of your net salary so that you don’t become overextended financially.