The Joint Medical Facilities Fund Act of 2026 establishes and codifies the authority for a Joint Medical Facility Fund under the Department of Veterans Affairs. The primary purpose of this fund is to facilitate the joint funding of designated combined federal medical facilities operated by both the Department of Defense and the Department of Veterans Affairs. Amounts can be transferred into the fund by both the Secretary of Defense and the Secretary of Veterans Affairs, based on a jointly established methodology reflecting mission-specific activities, workload, and costs. Additionally, medical care collections from third-party payers for services provided at these joint facilities may also be transferred into the fund. These funds will be available to support the operations of designated combined facilities, including expenses for capital equipment, real property maintenance, and minor construction projects. The bill specifically mentions the Captain James A. Lovell Federal Health Care Center as a facility that can utilize these funds for its operations. Administration of the fund will be governed by an executive agreement between the Secretaries of Defense and Veterans Affairs, which must include an independent review of the funding methodology and an integrated financial reconciliation process. This process is designed to accurately identify the fiscal contributions of each department to the fund, considering their distinct accounting and financial management practices. The bill also mandates a joint report within 180 days to identify other potential combined federal medical facilities.