Eligibility for Medicare is not based on income but on paying payroll tax for a minimum number of quarters of coverage. Individuals who have compiled enough quarters of coverage to be eligible for Social Security or railroad retirement benefits are also eligible for Medicare.
Individuals must be U.S. citizens or resident aliens to qualify for Medicare. The number of quarters of coverage necessary varies depending on whether the person is eligible for Medicare on the basis of age, disability or end-stage renal disease. Those eligible for Social Security based on work performance who are 65 or over receive free Medicare Part A coverage and are automatically eligible for Part B coverage. People age 65 or over who do not have a sufficient number of work quarters of coverage for Social Security insurance can purchase Medicare Part A and B coverage. Spouses of fully insured individuals are also eligible for Medicare, as are dependent parents whose insured child has died.
Those under 65 eligible for Medicare include people who receive Social Security or railroad disability benefits for at least 24 months and disabled widows, widowers or children of insured workers who are disabled, retired or deceased. Insured individuals who have had a kidney transplant or receive regular dialysis treatments also qualify for Medicare.