Medicare is a national health insurance program in the United States, begun in 1966 under the Social Security Administration (SSA) and now administered by the Centers for Medicare and Medicaid Services (CMS). It provides health insurance for Americans aged 65 and older, younger people with some disability status as determined by the Social Security Administration, as well as people with end stage renal disease and amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease).
In 2018, Medicare provided health insurance for over 59.9 million individuals—more than 52 million people aged 65 and older and about 8 million younger people. On average, Medicare covers about half of healthcare expenses of those enrolled. Medicare is funded by a combination of a payroll tax, beneficiary premiums and surtaxes from beneficiaries, co-pays and deductibles, and general U.S. Treasury revenue.
According to annual Medicare Trustees reports and research by the government’s MedPAC group, enrollees almost always cover remaining out-of-pocket costs with additional private insurance, by joining a public Medicare health plan, or both.
Medicare is divided into four Parts. Medicare Part A covers hospital (inpatient, formally admitted only), skilled nursing (only after being formally admitted to a hospital for three days and not for custodial care), and hospice services. Part B covers outpatient services including some providers’ services while inpatient at a hospital, outpatient hospital charges, most provider office visits even if the office is “in a hospital”, and most professionally administered prescription drugs. Part D covers mostly self-administered prescription drugs. Part C is an alternative called Managed Medicare which allows patients to choose health plans with at least the same service coverage as Parts A and B (and most often more), often the benefits of Part D, and always an annual out-of-pocket spend limit which A and B lack. A beneficiary must enroll in Parts A and B first before signing up for Part C. (Source Wikipedia)