The timeframe for enrolling in a Medicare plan is called an enrollment period. You have a seven-month window around the month you turn 65 to first sign up for a Medicare plan. If you miss the right time to enroll, your coverage may be delayed, or you could face penalties later on.
Open enrollment runs from Oct. 15 to Dec. 7 every year during which you can change Part D plans or Medicare Advantage plans for the following year, or switch between Medicare Advantage and original Medicare. Advantage enrollees also can switch to a new Advantage plan or original Medicare between Jan. 1 and March 31. And if a Medicare Advantage plan or Part D plan available in your area has a five-star quality rating, you can switch to that plan outside of the open enrollment period.
There are other enrollment periods, too, in addition to the seven-month initial enrollment period. If you missed signing up for Part B during that initial enrollment period and you aren't working (or aren't covered by your spouse's employer coverage), you can sign up for Part B during the general enrollment period that runs from Jan. 1 to March 31. Coverage will begin on July 1. But you will have to pay a 10% penalty for life for each 12-month period you delay in signing up for Part B. Those who are covered by a current employer's plan, though, can sign up later without penalty during a special enrollment period, which lasts for eight months after you lose that employer coverage. If you miss your special enrollment period, you will need to wait until the general enrollment period to sign up.