Medicare enrollment periods: when you can sign up and switch

You cannot join, switch or drop a Medicare plan whenever you like. There are set windows, called enrollment periods, and each one allows different changes. These are the three that apply to almost everyone.

Your Initial Enrollment Period: seven months around 65

This is generally when you turn 65. It lasts 7 months: it starts 3 months before the month you turn 65 and ends 3 months after that month. Someone who turns 65 in June can sign up from March through September.

You may be eligible earlier if you have a disability, End-Stage Renal Disease, or ALS.

During this period you can join any plan. You need both Part A and Part B to join a Medicare Advantage Plan, and either Part A or Part B to join a Medicare drug plan.

Open Enrollment: October 15 to December 7

Every year, in this window, you can:

• Join, drop or switch to another Medicare Advantage Plan, with or without drug coverage.
• Switch from Original Medicare to a Medicare Advantage Plan, or the other way round.
• Join, drop or switch a Medicare drug plan if you are in Original Medicare.

The change takes effect on January 1 of the next year. The plan has to get your request by December 7, so leaving it to the last day is a risk.

Medicare Advantage Open Enrollment: January 1 to March 31

This one is only for people already in a Medicare Advantage Plan. You can switch to another Medicare Advantage Plan, or drop yours and go back to Original Medicare. If you go back, you can also join a separate drug plan.

When your coverage starts

In your Initial Enrollment Period it depends on timing. Ask to join a plan before your Part A or Part B starts, and the plan's coverage starts the same day they do. Ask afterwards, and it starts on the first of the month after the plan gets your request.

If you picked a Medicare Advantage Plan first

You get a second look. If you joined a Medicare Advantage Plan during your Initial Enrollment Period, you can change to another one, or go back to Original Medicare, within the first 3 months you have Medicare Part A and Part B.

Why it is worth getting the dates right

Missing your window can mean a late enrollment penalty that lasts as long as you have the coverage. The enrollment periods page works out your own seven months from your birthday, and the penalty calculator shows what a late start costs.