The US Department of Defense has made "minimal progress" in accounting for F-35 parts worth approximately $31 billion, according to a US Government Accountability Office (GAO) report published on November 9, 2026. As of March 2026, the program held about 26 million parts at more than 700 contractor- and government-managed facilities worldwide, serving the US military, seven partner nations and 12 foreign military sales customers. DoD officials said its total value was likely understated.

The F-35 Joint Program Office tracks the inventory through its Enterprise Logistics Management System (ELMS), which does not interface directly with the prime contractors' property management systems, and contractors submit data on the shared spares pool quarterly. In a December 2025 contractor submission, only 29% of records included serial numbers. As of March 2026, about 17,000 parts undergoing maintenance or repair, valued at approximately $1.3 billion, had not been entered into ELMS, and DoD officials said their value could reach $2.5 billion once missing costs were included. The JPO's latest physical inventory also failed to fully verify whether recorded parts existed or whether the records were complete, relying on data from a prime contractor whose property management system had received a "disapproved" rating from the Defense Contract Management Agency. The Pentagon is now working toward its first full inventory under a new audit effort, targeted for March 2027.

More than a million reported parts losses remain unresolved: in May 2023, GAO reported that one prime contractor had recorded losses involving more than one million F-35 parts, valued at over $85 million, between May 2018 and October 2022, and three years later the JPO still did not know the status of those losses. Under a one-time bulk reporting process authorized by DCMA in June 2025, the contractor submitted about $28 million in losses dating from 2012 through 2025, and DCMA found the contractor financially liable for approximately $6 million, but JPO officials could not determine whether any of the newly submitted losses overlapped with the $85 million identified in 2023. DoD accepted all four new GAO recommendations, while 26 of the 34 recommendations previously issued by GAO and the DoD Inspector General remain open. Auditors have reported an F-35-related material weakness since fiscal year 2019, and DoD has received a disclaimer of opinion in every full audit through fiscal year 2025. The JPO's Global Support Solution Reset aims to raise the mission-capable rate from 44% in fiscal year 2025 to 80% by 2030; GAO estimated in June 2026 that the plan would require about $13.7 billion in additional US funding through fiscal year 2031, including $7.3 billion for spare parts and repair materials.