Medicare AEP vs. the Medicare Advantage OEP: Two Different Windows

There are two Medicare enrollment windows that people routinely confuse, and the confusion is expensive because Medicare deadlines do not bend. If you miss the right window, the answer is usually to wait a year.

They are not the same window, they do not do the same things, and not everybody can use both.

The Annual Enrollment Period

This is the fall window, and it is the one most people mean when they say "open enrollment." It runs from October 15 through December 7, every year, set by 42 CFR 422.62.

Anything you change takes effect January 1. Not immediately, and not the following month. This trips people up when they enroll in October and expect a new card in November.

What you can do

• Join a Medicare Advantage plan, coming from Original Medicare
• Switch from one Medicare Advantage plan to another
• Drop Medicare Advantage and return to Original Medicare
• Join a standalone Part D drug plan
• Switch from one Part D plan to another
• Drop Part D coverage entirely, though think hard about the penalty first

You can make as many changes as you like during the window. The last request the plan receives by the deadline is the one that counts. So if you enroll in November and change your mind in early December, that is fine.

What it does not do

The Annual Enrollment Period does not give you any rights to buy a Medicare Supplement policy. Medigap has its own separate rules and its own one-time open enrollment period tied to your Part B start date. You can leave a Medicare Advantage plan during AEP and find that no Medigap carrier will accept you afterward. Those are two independent facts and both can be true at once.

The Medicare Advantage Open Enrollment Period

This is the first-quarter window, running January 1 through March 31. It is a much narrower tool than people assume.

Who can use it

Only people already enrolled in a Medicare Advantage plan. That includes anyone who joined one through their Initial Enrollment Period, so it is not strictly limited to people enrolled on January 1.

If you are on Original Medicare, this window does not exist for you. You cannot use it to join a Medicare Advantage plan. That single restriction accounts for most of the confusion.

What it allows

One change. Either:

• Switch to a different Medicare Advantage plan, with or without drug coverage, or
• Drop Medicare Advantage, return to Original Medicare, and join a standalone Part D plan

One change, then the window closes for you. It is not a second shopping season.

Changes take effect the first of the month after the plan receives your request — so a February switch starts March 1. That is different from AEP, where everything starts January 1.

What it does not allow

• Joining Medicare Advantage from Original Medicare
• Switching from one standalone Part D plan to another while staying on Original Medicare
• Making multiple changes
• Any guaranteed right to buy a Medigap policy

That last one deserves emphasis. Leaving Medicare Advantage during this window returns you to Original Medicare, and Original Medicare has no cap on your annual out-of-pocket costs. If you cannot get a Medigap policy because of underwriting, you are exposed. Sort out the Medigap side before you drop the Advantage plan, not after.

The short version

The Annual Enrollment Period in the fall is for everyone with Medicare, allows unlimited changes across Advantage and Part D, and takes effect January 1.

The Medicare Advantage Open Enrollment Period in the first quarter is only for people already in an Advantage plan, allows one change, and takes effect the following month.

The fall window is for shopping. The first-quarter window is for fixing a plan that turned out to be wrong.

Special Enrollment Periods

Outside both windows, certain life events open a Special Enrollment Period. Briefly, the common ones:

• Moving out of your plan's service area, or to an area with new options
• Losing employer or union coverage, including retiring
• Entering, living in, or leaving a skilled nursing facility or long-term care facility
• Your plan leaving your area or ending its Medicare contract
• Becoming eligible for Extra Help or Medicaid, or losing that eligibility
• Qualifying for a chronic condition special needs plan

Each has its own window and its own rules about what you can change. If something significant changes in your life, ask whether it opened a Special Enrollment Period rather than assuming you have to wait for fall. People wait unnecessarily all the time.

What to do next

Two habits will keep you out of trouble.

Read the Annual Notice of Change your plan sends every September. It states exactly what is changing for January — premium, copays, drug tiers, network. It arrives looking like junk mail and it is the single most important document your plan sends you.

Then review your coverage every fall even if you are happy. Plans change around you. The plan that was right last year may not be the same plan in January.

If you are in an Advantage plan and January has already made you uneasy, do not wait until next fall. Let's talk during the first quarter while you still have a move available.