The "Mental and Physical Health Care Comorbidities Act of 2025" proposes a new demonstration program under Medicare, running from October 2025 to September 2030. Its primary goal is to test and evaluate innovative approaches by eligible hospitals to collaboratively treat mental and physical health comorbidities and address adverse social determinants of health among applicable individuals. The program aims to improve care quality, health outcomes, and reduce healthcare costs for vulnerable populations. Under this program, the Secretary of Health and Human Services will coordinate with participating hospitals to identify, validate, and disseminate evidence-based best practices. Hospitals must submit detailed plans outlining their proposed innovations, target populations, community partnerships, and expected impacts on health outcomes and costs. These plans will also address how innovations might inform future payment reforms under Medicare and Medicaid. Participating hospitals, which include specific types of rural, large teaching, and small urban safety net facilities, will enter into agreements with the Secretary and receive annualized payments to support their initiatives. The bill defines "applicable individuals" as those with mental and physical health comorbidities who are subsidy-eligible, Medicaid enrollees, or uninsured. A learning collaborative will be established to facilitate information sharing and reporting among participants and other interested parties. The innovations covered by the program include implementing interdisciplinary care teams, integrating mental health services into medical homes, improving electronic health records for care coordination, and addressing social determinants of health through "wrap around" services and home- and community-based care. Upon completion, the Secretary must submit a comprehensive report to Congress evaluating the program's activities, their impact on various objectives like access, quality, cost reduction, and justice system involvement, and provide recommendations for future legislative or administrative actions.