Administration at 1-800-772-1213 to enroll in Medicare or to ask questions about whether you are eligible. You can also visit their web site at www.socialsecurity.gov.
The Medicare.gov Web site also has a tool to help you determine if you are eligible for Medicare and when you can enroll. It is called the Medicare Eligibility Tool.
If you already receive benefits from Social Security:
If you already get benefits from Social Security or the Railroad Retirement Board, you are automatically entitled to Medicare Part A (Hospital Insurance) and Part B (Medical Insurance) starting the first day of the month you turn age 65. You will not need to do anything to enroll. Your Medicare card will be mailed to you about 3 months before your 65th birthday. If your 65th birthday is February 20, 2010, your Medicare effective date would be February 1, 2010. (Note: if your birthday is on the 1st day of any month, Medicare Part A and Part B will be effective the 1st day of the prior month. For example, if your 65th birthday is February 1, 2010, your Medicare effective date would be January 1, 2010.)
If you are not getting Social Security benefits:
If you are not getting Social Security benefits, you can apply for retirement benefits online. If you would like to file for Medicare only, you can apply by calling 1-800-772-1213.
If you are under age 65 and disabled:
If you are under age 65 and disabled, and have been entitled to disability benefits under Social Security or the Railroad Retirement Board for 24 months, you will be automatically entitled to Medicare Part A and Part B beginning the 25th month of disability benefit entitlement. You will not need to do anything to enroll in Medicare. Your Medicare card will be mailed to you about 3 months before your Medicare entitlement date. (Note: If you are under age 65 and have Lou Gehrig's disease (ALS), you get your Medicare benefits the first month you get disability benefits from Social Security or the Railroad Retirement Board.) For more information about enrollment, call the Social Security Administration at 1-800-772-1213 or visit the Social Security web site. See also Social Security's Medicare FAQs.
For more information, see Medicare.gov