Medicaid in the United States is a social health care program for families and individuals with limited resources. The Health Insurance Association of America describes Medicaid as a "government insurance program for persons of all ages whose income and resources are insufficient to pay for health care". Medicaid is the largest source of funding for medical and health-related services for people with low income in the United States. It is a means-tested program that is jointly funded by the state and federal governments and managed by the states, with each state currently having broad leeway to determine who is eligible for its implementation of the program. States are not required to participate in the program, although all have since 1982. Medicaid recipients must be U.S. citizens or legal permanent residents, and may include low-income adults, their children, and people with certain disabilities. Poverty alone does not necessarily qualify someone for Medicaid.
The Patient Protection and Affordable Care Act significantly expanded both eligibility for and federal funding of Medicaid. Under the law as written, all U.S. citizens and legal residents with income up to 133% of the poverty line, including adults without dependent children, would qualify for coverage in any state that participated in the Medicaid program. However, the United States Supreme Court ruled in National Federation of Independent Business v. Sebelius that states do not have to agree to this expansion in order to continue to receive previously established levels of Medicaid funding, and many states have chosen to continue with pre-ACA funding levels and eligibility standards.