(Taken from Medicare.gov Website)
Who is eligible for Medicare?
Generally, Medicare is available for people age 65 or older, younger people with disabilities and people with End-Stage Renal Disease (permanent kidney failure requiring dialysis or transplant). Medicare has two parts, Part A (Hospital Insurance) and Part B (Medicare Insurance). You are eligible for premium-free Part A if you are age 65 or older and you or your spouse worked and paid Medicare taxes for at least 10 years. You can get Part A at age 65 without having to pay premiums if:
You are receiving retirement benefits from Social Security or the Railroad Retirement Board.
You are eligible to receive Social Security or Railroad benefits but you have not yet filed for them.
You or your spouse had Medicare-covered government employment.
To find out if you are eligible and your expected premium, go the Medicare.gov eligibility tool.
If you (or your spouse) did not pay Medicare taxes while you worked, and you are age 65 or older and a citizen or permanent resident of the United States, you may be able to buy Part A. If you are under age 65, you can get Part A without having to pay premiums if:
You have been entitled to Social Security or Railroad Retirement Board disability benefits for 24 months. (Note: If you have Lou Gehrig's disease, your Medicare benefits begin the first month you get disability benefits.)
You are a kidney dialysis or kidney transplant patient.
While most people do not have to pay a premium for Part A, everyone must pay for Part B if they want it. This monthly premium is deducted from your Social Security, Railroad Retirement, or Civil Service Retirement check. If you do not get any of these payments, Medicare sends you a bill for your Part B premium every 3 months.
Prescription Drug Coverage
Since January 1, 2006, everyone with Medicare, regardless of income, health status, or prescription drug usage has had access to prescription drug coverage. For more information, you may wish to visit the Prescription Drug Coverage site.
For Step by Step Eligibility Guidelines From The Social Security Booklet