As specified in Title 14 of the Code of Federal Regulations (14 CFR) part 91, no person may operate an aircraft in controlled airspace under IFR unless that person has filed an IFR flight plan.

FAR 91.169 - IFR Flight Plans Must provide information required by FAR 91.153: Aircraft ID, type, pilot, departure point, departure time, route, altitude, TAS, destination, time en-route, fuel on board, souls on board, and “any other information the PIC or ATC believes is necessary for ATC purposes.”