The Centers for Medicare and Medicaid Services is a component of the Department of Health and Human Services. It oversees health coverage for more than 160 million Americans across Medicare (seniors and disabled people), Medicaid (low-income people), CHIP, and the ACA marketplace. CMS sets reimbursement rates, establishes program integrity requirements, and has authority to withhold federal matching funds from states found to be non-compliant. Mehmet Oz was confirmed as CMS Administrator by the Senate in 2025 after Trump nominated him.