The John Lewis Equality in Medicare and Medicaid Treatment Act of 2026 amends federal healthcare law to require the Center for Medicare and Medicaid Innovation to prioritize health equity and address health disparities when testing new payment and service delivery models for Medicare and Medicaid beneficiaries. The bill mandates that the agency consult with specialized offices focused on minority health, rural health, and women's health when developing new models, and requires models beginning in 2027 or later to explicitly address health equity and social determinants of health such as housing, food security, and transportation. The legislation establishes a specific social determinants of health payment model to be tested by December 31, 2027, focusing on behavioral health services, conditions affecting dual Medicare-Medicaid beneficiaries, underserved areas, and pregnant and postpartum women. Future reports to Congress must include information about health equity improvements, estimated federal savings from reducing disparities, and the effectiveness of interventions addressing social determinants of health. The bill affects Medicare and Medicaid beneficiaries, healthcare providers in underserved areas, and federal health agencies involved in payment model testing and oversight.