Centers for Medicare & Medicaid Services (CMS)

Core programs and responsibilities

CMS's principal responsibilities can be grouped into program administration, regulation, and quality oversight. The agency operates Medicare, the federally administered health insurance program commonly associated with older adults, and supports the policy and payment rules that govern Medicare services. In partnership with states, CMS oversees Medicaid, a means-tested program for low-income individuals and families, and the State Children's Health Insurance Program that extends coverage to children in families with incomes too high for Medicaid but lacking private insurance.

In addition to these programs, CMS implements administrative simplification provisions of the Health Insurance Portability and Accountability Act (HIPAA) that pertain to standard transaction formats and identifiers. It also administers clinical laboratory quality standards under the Clinical Laboratory Improvement Amendments and uses a survey and certification process to monitor compliance and quality in long-term care facilities such as nursing homes. CMS had a central role in the establishment and ongoing oversight of HealthCare.gov and related federal marketplace activities.

Functions, tools, and policy initiatives

The agency issues regulations, guidance, and payment rules that affect providers, health plans, and states. CMS designs payment systems for hospitals, physicians, and other providers; conducts audits and oversight; and promotes quality improvement through measures, public reporting, and incentive programs. It maintains large administrative datasets derived from claims and enrollment records that support policymaking, research, and program integrity efforts. In recent decades CMS has promoted alternative payment models intended to link payment to quality and value rather than volume.

• Program administration: managing enrollment, claims processing, and benefit rules for Medicare, and collaborating with states on Medicaid policy and financing.
• Regulation and standards: issuing rules for payments, coding, electronic transactions, and laboratory and facility quality.
• Quality and enforcement: surveying nursing homes, certifying compliance with CLIA, and using performance measures to improve care.
• Data and research: collecting claims and quality data that inform national health statistics and payment reforms.

CMS has evolved from earlier organizational forms and names to meet changing policy priorities and program complexity. Its influence extends across the health care system because Medicare and Medicaid together account for a large share of health care financing. Changes in CMS policies—whether in payment rates, coverage rules, or quality initiatives—often shape provider behavior, state program design, and the broader market for health services and medical devices.

For further general information and program details, see entries on Medicare and Medicaid. The agency's activities touch on diverse topics including health information standards, long-term care quality, laboratory regulation, marketplace administration, and efforts to control fraud and waste.