Medicaid is the United States health program for families and individuals with low income and 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 ameans-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 currently do. 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 Provisions of the Patient Protection and Affordable Care Act will significantly expand both eligibility for and federal funding of Medicaid beginning on January 1, 2014. 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 existing levels of Medicaid funding, and many states have chosen to continue with current funding levels and eligibility standards.

As of 2013, Medicaid is a program intended for those with low income, but a low income is not the only requirement to enroll in the program. Eligiblity is categorical -- that is, to enroll you must be a member of a category defined by statute; some of these categories include low-income children below a certain age, pregnant women, parents of Medicaid-eligible children who meet certain income requirements, and low-income seniors. The details of how each category is defined varies from state to state.

People with disabilities who do not have a work history and who receive Supplemental Security Income, or SSI, are enrolled in Medicaid as a mechanism to provide them with health insurance. Persons with a disability, including blindness or physical disability, deafness, or mental illness can apply for SSI. However, in order to be enrolled, applicants must prove that they are disabled to the point of being unable to work. In recent years, a substantial liberalization occurred in the field of individual disability income insurance, which provides benefits when an insured person is unable to work because of illness or injury (HIAA, pg.13).

Some states operate a program known as the Health Insurance Premium Payment Program (HIPP). This program allows a Medicaid recipient to have private health insurance paid for by Medicaid. As of 2008 relatively few states had premium assistance programs and enrollment was relatively low. Interest in this approach remained high, however.

Included in the Social Security program under Medicaid are dental services. These dental services are an optional service for adults above the age of 21; however, this service is a requirement for those eligible for Medicaid and below the age of 21. Minimum services include pain relief, restoration of teeth and maintenance for dental health. Early and Periodic Screening, Diagnostic and Treatment (EPSDT) is a mandatory Medicaid program for children that aims to focus on prevention, early diagnosis and treatment of medical conditions. Oral screenings are not required for EPSDT recipients and they do not suffice as a direct dental referral. If a condition requiring treatment is discovered during an oral screening, the state is responsible for taking care of this service, regardless of whether it is covered on that particular Medicaid plan.

Unlike Medicaid, Medicare is a social insurance program funded at the federal level and focuses primarily on the older population. As stated in the CMS website, Medicare is a health insurance program for people age 65 or older, people under age 65 with certain disabilities, and people of all ages with end stage renal disease. The Medicare Program provides a Medicare part A which covers hospital bills, Medicare Part B which covers medical insurance coverage, and Medicare Part D which covers prescription drugs.

Medicaid is a program that is not solely funded at the federal level. States provide up to half of the funding for the Medicaid program. In some states, counties also contribute funds. Unlike the Medicare entitlement program, Medicaid is a means-tested, needs-based social welfare or social protection program rather than a social insurance program. Eligibility is determined largely by income. The main criterion for Medicaid eligibility is limited income and financial resources, a criterion which plays no role in determining Medicare coverage. Medicaid covers a wider range of health care services than Medicare. Some people are eligible for both Medicaid and Medicare and are known as Medicare dual eligibles.  In 2001, about 6.5 million Americans were enrolled in both Medicare and Medicaid. In 2013, approximately 9 million people qualified for Medicare and Medicaid.

Medicaid is a joint federal-state program that provides health coverage or nursing home coverage to certain categories of low-asset people, including children, pregnant women, parents of eligible children, people with disabilities and elderly needing nursing home care. Medicaid was created to help low-asset people who fall into one of these eligibility categories "pay for some or all of their medical bills."

There are two general types of Medicaid coverage. "Community Medicaid" helps people who have little or no medical insurance. Medicaid nursing home coverage pays all of the costs of nursing homes for those who are eligible except that the recipient pays most of his/her income toward the nursing home costs, usually keeping only $66.00 a month for expenses other than the nursing home.

While Congress and the Centers for Medicare and Medicaid Services (CMS) set out the general rules under which Medicaid operates, each state runs its own program. Under certain circumstances, an applicant may be denied coverage. As a result, the eligibility rules differ significantly from state to state, although all states must follow the same basic framework.