When you first become eligible for Medicare at 65, you get a seven-month Initial Enrollment Period. It starts three months before the month you turn 65, includes your birthday month, and ends three months after it, according to Medicare.gov. Enter a birth date to see your window.
Good to know
If your birthday falls on the first day of a month, Medicare treats you as turning 65 in the previous month, so your window starts and ends a month earlier. This calculator already accounts for that.
Some people are enrolled automatically, for example people already receiving Social Security retirement benefits when they turn 65. Others have to sign up. If you do not sign up when you first can and you do not have other qualifying coverage, you may face a later enrollment and, for Part B and Part D, higher premiums for as long as you have the coverage. See the Part D late-enrollment penalty estimator.
Different rules apply if you qualify for Medicare before 65, for example because of a disability. For your own situation, confirm with Medicare.gov, the Social Security Administration or a licensed agent.