Medicare Annual Enrollment 2025: Your Top Questions Answered

Every year, millions of Medicare beneficiaries let their plans auto-renew without taking a second look. And every year, a lot of them end up paying more, losing access to a doctor they liked, or finding out a prescription they rely on suddenly costs a lot more than it used to. The Annual Enrollment Period exists so you don't have to just accept whatever your plan decided to do this year. Below are the questions we hear most often from clients this time of year.

What is Medicare Annual Enrollment, and why does it matter?

The Medicare Annual Enrollment Period, often called AEP or open enrollment, is the window each year when people already on Medicare can make changes to their Medicare Advantage plan (Part C) or their prescription drug plan (Part D). It runs from October 15 through December 7, and whatever you change takes effect on January 1 of the following year.

It matters because carriers are allowed to change their plans every single year. Premiums go up. Benefits get added or cut. Drug formularies, the list of medications a plan covers and what tier they fall into, get updated. Provider networks shift too, so a doctor who was in-network this year might not be next year. Skip your review during AEP and you're effectively agreeing to every change your carrier made, whether or not it actually works for you.

Who can actually make changes during open enrollment?

If you're already enrolled in a Medicare Advantage plan or a standalone Part D drug plan, AEP is your window. You can switch from one Medicare Advantage plan to another, drop Medicare Advantage entirely and move back to Original Medicare, join a standalone Part D plan if you're on Original Medicare, or switch from one Part D plan to another.

Two things AEP does not cover. You generally cannot use it to enroll in Medicare Part A or Part B if you missed your Initial Enrollment Period, that requires a separate process and often comes with a penalty. And you cannot use it to buy or change a Medigap supplemental policy. Those follow their own rules, and in most states, medical underwriting applies outside of specific windows.

I'm turning 65 soon. Does this apply to me?

Not yet. If you're approaching 65, you have your own window called the Initial Enrollment Period. It's seven months total: it opens three months before your birthday month, includes your birthday month, and runs three months after.

Missing that window gets expensive fast. Skip signing up for Part B when you're first eligible and you could face a late enrollment penalty, an extra 10% added to your monthly premium for every 12-month period you were eligible but didn't enroll. That penalty does not go away. There are exceptions if you have qualifying employer coverage, but the rules get confusing quickly, so it's worth confirming your specific situation before your birthday rather than assuming you're covered.

What is the Medicare Advantage Open Enrollment Period?

This is a separate, shorter window that runs January 1 through March 31 each year, and it's easy to confuse with AEP. The Medicare Advantage Open Enrollment Period, or MA-OEP, is only for people already in a Medicare Advantage plan at the start of the year. During it, you can switch to a different Advantage plan or drop it altogether and return to Original Medicare with a standalone Part D plan.

What you cannot do is join a Medicare Advantage plan from scratch if you weren't already in one. That's what fall's Annual Enrollment Period is for. Think of MA-OEP as a second chance if your new plan turns out not to fit once you're actually using it.

What is a Special Enrollment Period, and when does it apply?

A Special Enrollment Period, or SEP, lets you make changes outside the standard windows when certain life events happen. These aren't loopholes. They're built into the system to protect people whose circumstances change without warning.

Common triggers include moving to a new ZIP code your current plan doesn't serve, losing employer coverage, qualifying for the Extra Help low-income subsidy, gaining or losing Medicaid eligibility, or entering or leaving a nursing home. The rules vary a lot depending on which event applies to you, including how long you have to act and what plans you're allowed to switch into. This is one area where a knowledgeable advisor genuinely helps, since missing an SEP window can leave you stuck in a plan that doesn't fit for the rest of the year.

What should I actually review before changing my plan?

This is the most practical question of the bunch, and it's the one most people skip. Here's what to go through before you decide anything:

• Annual Notice of Change (ANOC): your carrier sends this every September. Read it. It spells out every change coming to your plan next year.
• Drug formulary: confirm each medication you take is still covered, and check what tier it falls into. One drug moving up a tier can cost hundreds more a year.
• Provider network: verify your primary care doctor, specialists, and preferred hospitals are still in-network for next year.
• Out-of-pocket maximum: check whether your annual cost cap changed. This matters most if you have significant health needs.
• Cost-sharing: look at copays and coinsurance for the services you actually use, not just the headline premium.
• Extra benefits: dental, vision, hearing, and fitness programs vary a lot between plans. If you use these, confirm they're still included.
• Low-income assistance: if your finances have changed, you may now qualify for Extra Help or a Low Income Subsidy that lowers your drug costs.

The Annual Notice of Change is arguably the most important document you'll get all year as a Medicare beneficiary, and most people toss it without reading it. Don't. It tells you exactly what's shifting in your plan and gives you what you need to decide whether to stay put or switch.

Can I drop Medicare Advantage and go back to Original Medicare?

Yes, and it's a more common move than people assume. During AEP, you can drop Medicare Advantage and return to Original Medicare, Parts A and B. You can also pick up a standalone Part D plan at the same time to keep your drug coverage intact.

The tradeoff to think through first is losing the extras. Medicare Advantage plans often bundle in dental, vision, hearing, and fitness coverage that Original Medicare doesn't include. Go back to Original Medicare and those extras go with the old plan. If you want to add a Medigap supplemental policy to help cover the gaps, check your state's rules first. In most states, insurers can use medical underwriting outside of specific protected windows, meaning they can deny coverage or charge more based on your health history. That's worth knowing if you have any pre-existing conditions.

What happens if I miss open enrollment?

If December 7 passes and you didn't make changes, you're generally locked into your current plan until next fall's Annual Enrollment Period, unless a life event qualifies you for a Special Enrollment Period. Your plan may have changed significantly for the new year, and without an SEP, you're stuck with it until October comes back around.

If you have Medicare Advantage, the MA Open Enrollment Period in January through March gives you one more shot to switch plans or return to Original Medicare. It's narrower than AEP and won't let you join Medicare Advantage fresh if you weren't already in a plan, but it's better than nothing.

The simplest fix is to put October 15 on your calendar every single year. Read your Annual Notice of Change when it lands in September, and make your decisions before December 7. Missing open enrollment is not the end of the world. It just means living with your current plan for another full year, whether or not it still fits.

Medicare decisions are some of the most consequential financial choices retirees make, and they come back around every year without fail. A plan that fit perfectly last year might not be the right one now, especially if your health, your medications, or your doctors have changed. Thirty minutes of review during AEP can save you from coverage gaps and costs you didn't see coming.