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Medicare Open Enrollment 2024 Guide

Everything you need to know about the annual election period, including opportunities to change coverage, eligibility details and enrollment deadlines

Louise Norris | October 12, 2023

What is Medicare open enrollment?

Medicare open enrollment – also known as the annual election period (AEP) or annual coordinated election period – refers to an enrollment window that takes place each fall, during which Medicare plan enrollees can reevaluate their existing Medicare coverage — whether it’s Original Medicare with supplemental drug coverage, or Medicare Advantage — and make changes if they want to do so.

This guide is all about Medicare’s annual election period. If you’re interested in learning about additional opportunities to enroll or change your Medicare coverage, we’ve covered those here.

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When is Medicare open enrollment?

Medicare open enrollment starts October 15 and continues through December 7 each year. (Extended enrollment opportunities are available to some people in areas where [FEMA] declares an emergency or major disaster that hampers their ability to complete their signup during the normal window.)

What plan changes can I make during the Medicare open enrollment period?

During the Medicare open enrollment period – if you’re already enrolled in Medicare coverage – 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 (PDP), and possibly a Medigap plan, although medical underwriting might be required for Medigap, depending on the state and the person’s circumstances).
  • Switch from one Medicare Advantage plan to another.
  • Switch from one Medicare Part D prescription drug plan (PDP) 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.

If I change my coverage at the start of the AEP, can I change my mind before the December 7 deadline?

Yes. You can change your mind and pick a different plan later in the AEP. There’s no limit on the number of plan changes you can make during the AEP.

The last plan selection you make will be the plan that takes effect January 1.

If I make a mistake when I change my coverage during the AEP, what can I do to fix it?

If you realize that you’ve made a mistake while the AEP is ongoing, you can simply pick a different plan instead (by the December 7 deadline) and the new choice will take effect on January 1.

If the AEP has ended and you’ve enrolled in a Medicare Advantage plan but believe you should have picked a different plan, you can use the Medicare Advantage Open Enrollment Period (MAOEP) to pick a different Advantage plan or switch to Original Medicare and a Part D plan.

For instance, maybe you picked an Advantage plan that doesn’t cover an expensive medication you need, or that doesn’t include a conveniently located hospital in its network. Or maybe you let your existing Advantage plan auto-renew and didn’t realize that the premium or benefits would be changing as of January. Regardless of the reason, the MAOEP gives people with Medicare Advantage one “do-over” opportunity at the start of the year.

The annual MAOEP window runs from January 1 to March 31.

If the AEP has ended and you’ve enrolled in a stand-alone Part D plan that doesn’t fit your needs, your options are more limited. There is nothing like the MAOEP to make changes to a stand-alone Part D plan. Changes to these plans can generally only be made during the fall AEP.

However, if you believe that you were given inaccurate or misleading information that led you to make the wrong plan choice, you can call 1-800-MEDICARE and explain the details. Depending on the circumstances, the call center may allow you to make a plan change at that point.

Who’s eligible to make coverage changes during Medicare open enrollment?

If you’re currently covered by Original Medicare or Medicare Advantage, then you’re eligible to make changes during open enrollment.

However, the annual Medicare open enrollment period does not apply to Medigap plans, which – in most states – are only guaranteed-issue during a beneficiary’s initial enrollment period, and during limited special enrollment periods. So to clarify, you cannot use the annual Medicare open enrollment period to enroll in a new Medigap plan on a guaranteed-issue basis. You can certainly apply for a new Medigap plan during this window – just as you can at any time of the year. But if your six-month initial enrollment period for Medigap has ended and you’re not in a trial right period, the Medigap insurer will use medical underwriting to determine your eligibility and premium.

(Note that as of 2024, there are 14 states that allow for at least some guaranteed-issue access to new Medigap plans, although in most cases it’s limited to switching from one Medigap plan to another with equal or lesser benefits.)

In addition, if you didn’t enroll in Medicare Part B when you were first eligible, you may not use the AEP to sign up. Instead, you’ll use Medicare’s general enrollment period, which runs from January 1 to March 31. The general enrollment period is 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. (Most people do not have the pay a premium for Part A.)

Learn more about Medicare’s general enrollment period.

Can I sign up for Medigap during the AEP?

You can certainly apply for a Medigap (Medicare supplement) plan during the AEP or at any other time of the year. But unlike Part D and Medicare Advantage plans, there is not a federally required annual enrollment opportunity for Medigap plans.

If you apply for a Medigap plan after your six-month initial enrollment period has passed, however, the Medigap insurer is likely to use medical underwriting to determine your eligibility and premium.

There are 14 states (as of 2024) that offer an annual window during which existing Medigap enrollees can select from at least some other plans without medical underwriting, and a few of those states also extend that option to people who are newly enrolling in Medigap.

How will plan costs change for 2024 Medicare coverage?

You can see a detailed summary of Medicare premium and out-of-pocket changes here. But in general:

How many people change their coverage during the AEP?

Most Medicare beneficiaries do not switch plans during Medicare’s AEP. An analysis by KFF found that over the course of a decade, the percentage of beneficiaries who switched to a different Part D plan ranged from 10% to 13% per year. And for Medicare Advantage beneficiaries it was even lower, ranging from 6% to 11%.

More troubling is the fact that seven out of ten beneficiaries didn’t even compare their coverage options during a recent open enrollment period. It may well be that the plan you already have will continue to be the best option for the coming year. But there’s no way to know that without actively comparing the available alternatives, and the majority of Medicare beneficiaries aren’t doing that.

What will happen if I don’t change my Medicare coverage during the annual election period?

If you don’t make a plan change, your existing coverage will renew for the 2023. But that could come with cost and benefit changes. The plan you have might have changes to its drug formulary (covered drug list) or its provider network, meaning that a specific medication or doctor may no longer be covered under the plan. And the plan could also have premium and/or cost-sharing structure changes.

This is why it’s so important to actively compare the available options each fall. You’ll want to check to see how your doctors and prescription will be covered in the coming year, both by the plan you already have and by the other plans that are available in your area.

After the annual election period ends, you will not be able to make a change to your stand-alone Part D plan until the next annual election period. If you have a Medicare Advantage plan, you will still have an opportunity to use the Medicare Advantage Open Enrollment Period (MAOEP) that runs from January through March. You can make just one plan change during this window.

But it’s important to note that the new plan selection would take effect in February at the earliest (and as late as April, depending on when you make the plan selection). This means your out-of-pocket costs for the year would reset to zero when the new plan starts, regardless of how much you had spent in the early part of the year under your old plan.

So, if there’s any chance you’ll want to make a plan change, the best approach is to select your new plan by the annual election period deadline (by December 7) so that the coverage takes effect January 1 and covers you for the entire year.

Louise Norris is an individual health insurance broker who has been writing about health insurance and health reform since 2006. She has written dozens of opinions and educational pieces about the Affordable Care Act for Her state health exchange updates are regularly cited by media who cover health reform and by other health insurance experts.

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