For most people, the first of the month that you turn 65 years old is when Medicare becomes active. However, for those who are past their 65th birthday and have had their insurance through their employer, they have the option to begin Medicare when they choose. Also, if you are receiving social security disability you are also eligible for Medicare no matter your age.
If you are receiving Social Security retirement benefits when you turn 65, you will automatically be enrolled in Medicare. If this is the case, you'll be automatically enrolled in Parts A and B of Medicare and you can expect to receive your Medicare benefits card about three months before you turn 65. If you are not receiving your Social Security retirement benefit when you turn 65, you will have to apply for Medicare either via online through the Social Security Administration's website or by going to a local social security office.
Either turning 65 or coming onto Medicare?
It depends on what kind of health insurance you have. If you have insurance through your employer or your spouse's employer and you are still working, you may not be required to enroll in Medicare as long as the company sponsoring your coverage has at least 20 employees. In this case, you'll have a special enrollment period after you (or your spouse) retire or leave that employer. If your insurance is through an employer you've already retired from, you still have to sign up at 65. If your employer has less then 20 employees, you MUST sign up for Medicare A and B when you turn 65. If you are required to sign up for Medicare Part B, and don't, you'll face a permanent penalty of 10% of the Medicare Part B premium for every year you were supposed to enroll but didn't.