Fill in the number of days indicating when the increased deposit will be made or specify a particular condition such as "upon removal of the inspection. A California Residential Purchase Agreement (RPA) is a legally binding contract between a buyer and seller.It lays out the terms of a real estate transaction. Below is an explanation of selected items in the Purchase Agreement you will be filling out once you have decided on a property. This form is made available to real estate professionals through an agreement with or purchase from the California Association of REALTORS®.