On February 6, 2023, about 1545 central standard time, a Cessna 425, N425Z, was substantially damaged when it was involved in an accident at Bismarck Municipal Airport (BIS), Bismarck, North Dakota. The pilot was not injured and the two passengers sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported an uneventful flight and landing at BIS. After taxiing to the ramp, the pilot proceeded to stop the airplane in front of a marshaller. After moving the throttles toward the ground idle position, the pilot observed the airplane turn left and reported that the right brake was inoperative. The pilot reported moving both propeller levers to the feather position and subsequently moved both throttles toward the reverse (beta) position. The airplane continued forward and struck a hangar, which substantially damaged the left wing. Postaccident examination of the braking system revealed the brake master cylinders were nearly empty of brake fluid, with no leaks observed. A review of maintenance logs revealed that the pilot, who was also a mechanic, recorded completion of the Phase 3 inspection of the Cessna 425 maintenance manual on May 21, 2022. The Phase 3 inspection includes servicing the brake master cylinders. The pilot/mechanic reported that during this inspection he checked the brake pads and checked for leaks around the brakes and the master cylinders. He depressed the brake pedals to find there was resistance; however, he reported that he did not check the fluid levels of the master cylinders during the inspection.