Most people qualify for Medicare when they turn 65. You qualify for it if you're eligible for Social Security or Railroad Retirement benefits. Or you may qualify on a spouse's (including divorced spouse's) record.  Others qualify because they are government employees not covered by Social Security who paid the Medicare part of the Social Security tax. In addition, if you've been getting Social Security disability benefits for 24 months or get Social Security disability benefits and have amyotrophic lateral sclerosis (Lou Gehrig's disease), you'll qualify for Medicare. You may also qualify if you have permanent kidney failure and you receive maintenance dialysis or a kidney transplant.

If you are already getting Social Security benefits, you'll automatically be enrolled in Medicare Parts A and B. However, because you must pay a premium for Part B coverage, you have the option of turning it down.  You will be contacted by mail a few months before you become eligible and given all the information you need.

If you are not already getting benefits when you turn 65, you should call or visit a Social Security office 3 months prior to your birthday so Social Security can help you decide if you should sign up for Medicare. You should do this even if you plan to continue working or do not think you have enough work credit under Social Security, because Medicare enrollment period rules are very strict.  If you would like to file for Medicare only, you can apply by calling 1-800-772-1213. The Social Security Administration’s representatives there can make an appointment for you at any convenient Social Security office. When you apply for Medicare, the Social Security Administration often also takes an application for monthly benefits.  If you want to apply, the Social Security Administration suggests that you apply for retirement benefits online.