Medicare open enrollment – also known as Medicare’s annual election period – runs from October 15 through December 7 each year. During this annual window, Medicare plan enrollees can reevaluate their coverage – whether it’s Original Medicare with Prescription drug coverage, or Medicare Advantage – and make changes or purchase new policies if they want to do so.

During the Medicare open enrollment period, you can:

• Switch from Original Medicare to Medicare Advantage (as long as you’re enrolled in both Medicare Part A and Part B, and you live in the Medicare Advantage plan’s service area).

• Switch from Medicare Advantage to Original Medicare (plus a Medicare Part D plan, and possibly a Medigap plan).

• Switch from one Medicare Advantage plan to another.

• Switch from one Medicare Part D prescription drug plan to another.

• Enroll in a Medicare Part D plan if you didn’t enroll when you were first eligible for Medicare. If you haven’t maintained other creditable coverage, a late-enrollment penalty may apply.

Medicare open enrollment: What you can’t do:

The annual Medicare open enrollment period does not apply to Medicare Supplement plans, which are only guaranteed-issue in most states during a beneficiary’s initial enrollment period and during limited special enrollment periods.

If you didn’t enroll in Medicare when you were first eligible, you cannot use the fall open enrollment period to enroll. Instead, you’ll use the Medicare general enrollment period, which runs from January 1 to March 31.

Medicare’s general enrollment period is for people who didn’t sign up for Medicare Part B when they were first eligible, and who don’t have access to a Medicare Part B special enrollment period. It’s also for people who have to pay a premium for Medicare Part A and didn’t enroll in Part A when they were first eligible.

If you enroll during the general enrollment period, your coverage will take effect July 1.