Rental Expense Manager (REM) is a comprehensive tool designed for tracking rental or investment property expenses efficiently. With REM, users can easily input expenses using their iPhone or other iOS devices, as well as upload data from existing excel or .csv files. The program offers the flexibility to generate output summaries in the form of PDF or .csv files, which can be conveniently shared via email. REM supports management of multiple properties, filing options, customizable expense categories, or standard Schedule E tax categories. It also provides user-friendly editing features and additional functionalities such as mortgage interest estimations and return on investment calculations.