A person eligible for Medicare must be a U.S. citizen or a permanent resident for a period not less than five years, according to eHealth. He should be 65 years and older and eligible for Social Security.
A person who is at least 65 years and eligible for Social Security, but is not receiving benefits yet, has an automatic qualification for Medicare part A but must enroll for part B if he wants to be a member of part B, states eHealth. A person who is already getting benefits from Social Security or the railway retirement board gets automatic qualification for both parts A and B and is eligible for benefits at the beginning of the month he turns 65.
A person who is under 65 years old can be eligible if he is permanently disabled and has been receiving disability benefits for at least two years, explains eHealth. A person with end-stage renal disease is eligible, but he must enroll. A person with Lou Gehrig's disease gets automatic enrollment in part A and B in the month the disability begins.
Members do not have to pay the Medicare part A premium if they or their spouses paid Medicare taxes during at least 10 years of services, equivalent to 40 quarters, says eHealth. There is a 10 percent penalty for those who did not enroll for part B of Medicare when they became eligible, for a period of 12 months.