What people are restricted from qualifying for Medicare?

Individuals age 65 or older are restricted from applying for Medicare if they aren't U.S. citizens or permanent legal residents. Most people younger than 65 are restricted from applying for Medicare, although some disabled individuals are eligible, according to the American Association of Retired Persons.

People who receive Social Security disability benefits for at least 24 months are eligible for Medicare at any age, as are people who have Lou Gehrig's disease. Most people age 65 or older qualify for Medicare's Part A free hospital benefits, but some people must pay premiums if they or their spouses were out of the workforce for much of their lives, AARP notes.