The District of Columbia Application For Certificate of Occupancy (CO) is a form required by the District of Columbia’s Department of Consumer and Regulatory Affairs (DORA) to obtain a Certificate of Occupancy. The Certificate of Occupancy shows that the building meets all necessary building and safety codes, and is approved for occupancy. There are two types of District of Columbia Application For Certificate of Occupancy: the Standard Application and the Rental Application. The Standard Application is for any construction or improvement work performed on a non-rental property. The Rental Application is for any construction or improvement work performed on a rental property. The application must be completed and submitted to the DORA along with the appropriate fees and any necessary supporting documents. Upon approval, the DORA will issue a Certificate of Occupancy, which must be displayed prominently in the building.