Medicare's Annual Enrollment Period runs from October 15 through December 7 each year

The Annual Enrollment Period (AEP) is the one time each year when you can change your Medicare coverage without a penalty. During these seven and a half weeks in the fall, you can switch between Original Medicare and Medicare Advantage plans, add or drop prescription drug coverage, or change which plan you're in. Any changes you make take effect on January 1 of the following year.

If you miss this window, you generally cannot change your coverage until the next October 15 — with a few exceptions for people who experience specific life events like moving, losing employer coverage, or becoming newly may be able to access for Medicare.

Key Takeaways

  • Annual Enrollment Period happens every year from October 15 through December 7, and changes take effect January 1.
  • You can switch between Original Medicare and Medicare Advantage, add or drop Part D prescription drug coverage, or change to a different plan during this window.
  • Missing the important date means you cannot change your coverage for a full year, except in cases of major life changes.
  • You should review your current coverage each fall to check for plan changes, premium increases, and whether your medications are still covered.
  • Medicare sends notices in September and early October to help you prepare, and you can compare plans on Medicare.gov or call 1-800-MEDICARE.

What you can change during Annual Enrollment Period

During the seven-week window, you have several options. You can switch from Original Medicare (Part A and Part B) to a Medicare Advantage plan, or go the opposite direction from Medicare Advantage back to Original Medicare. You can add Part D prescription drug coverage if you don't have it, drop it if you do, or switch to a different Part D plan. If you're already in a Medicare Advantage plan, you can change to a different Medicare Advantage plan.

You cannot, however, make changes to your Part B coverage itself during AEP — that window is during the Initial Enrollment Period when you first turn 65 or become Medicare-may be able to access. You also cannot switch between different Medigap (supplemental insurance) plans during AEP; Medigap has its own enrollment rules.

Why you should review your coverage each fall

Even if you're happy with your current plan, insurance companies change their plans every year. Your monthly premium may go up, your copays may change, your deductible might increase, or the pharmacy network might shrink. Medications you take could be dropped from your plan's formulary (the list of covered drugs), or moved to a higher cost tier. Doctors you see might leave the network.

Medicare sends you a notice called the "Annual Notice of Change" in September, and your insurance company sends its own notice in October. These documents spell out what's changing for your specific plan. Spending 30 minutes reviewing these notices and comparing your plan to others can save you hundreds of dollars a year and prevent gaps in your coverage.

How to compare plans and make changes

The easiest way to compare plans is on Medicare.gov. Go to the "Plan Finder" tool, enter your zip code and the medications you take, and the site will show you all available plans ranked by cost. You can see your out-of-pocket costs for the year, which doctors and pharmacies are in each network, and whether your drugs are covered.

You can also call 1-800-MEDICARE (1-800-633-4227) and speak with a representative who can walk you through your options. Many local Area Agencies on Aging and senior centers offer free counseling through programs like SHIP (State Health Insurance information Program) — these counselors know your state's plans inside and out and can answer questions specific to your situation.

Once you've decided on a plan, you can enroll online through Medicare.gov, by phone at 1-800-MEDICARE, by mail using the enrollment form that comes with your plan materials, or directly through the insurance company's website or phone number.

What happens if you miss the important date

If October 15 to December 7 passes and you haven't made a change, you're locked into your current coverage for the entire year. You cannot switch plans, add or drop prescription drug coverage, or change from Original Medicare to Medicare Advantage (or vice versa) until the next October 15.

The main exceptions are may have access to Life Events: if you move out of your plan's service area, lose employer or union coverage, become newly may be able to access for Medicare, experience a death in your family, or have a significant change in income, you may be able to make changes outside of AEP. You typically have 60 days from the event to make your change. You'll need to contact Medicare or your plan directly to report the event and ask whether you're may be able to access for this exception.

When to start preparing for Annual Enrollment Period

Start thinking about your coverage in September, when Medicare begins sending notices. Pull together your current insurance card, your list of medications, and the names of the doctors you see regularly. If you're not sure what plan you're in or what coverage you have, call the number on your Medicare card.

In early October, sit down with the Annual Notice of Change from your current plan and your insurance company's notice. Highlight anything that's changing — premium, deductible, copays, formulary changes. Then use Medicare.gov's Plan Finder to see whether your current plan is still the best option for you, or whether a different plan would cost less or cover your needs better.

Make your decision and enroll by December 7. If you enroll by December 7, your new coverage starts January 1. If you enroll after December 7, your coverage won't start until later in January or February, depending on when you enroll.

Special situations: when you get extra time

If you're newly turning 65 or newly becoming Medicare-may be able to access, you have your own enrollment window called the Initial Enrollment Period, which is three months before, the month of, and three months after your birthday or may be able to access date. This is separate from AEP.

If you're still working and covered by an employer or union health plan, you may have different rules. Some employers let you stay on their plan past 65 and delay Medicare enrollment. Talk to your employer's benefits office about how this works and when you need to enroll in Medicare to avoid penalties.

If you're on Medicaid (state health insurance for low-income people), you may have additional enrollment windows or different rules in your state. Contact your state Medicaid office or call 1-800-MEDICARE to understand how this affects your Medicare choices.

Frequently Asked Questions

What if I enroll after December 7?

Your new coverage will start later — usually the first day of the month after you enroll, but sometimes later depending on when exactly you submit your enrollment. For example, if you enroll on December 15, your coverage might not start until February 1. This is why it's important to enroll before December 7 if you want your new plan to start on January 1.

Can I change my mind after I enroll?

Yes, but only during the Annual Enrollment Period. If you enroll in a new plan on November 1 and then change your mind on November 20, you can enroll in a different plan — as long as it's still before December 7. Once December 7 passes, you're locked in until next October 15.

Do I have to do anything if I want to keep my current plan?

No. If you're happy with your current plan and nothing is changing, you don't need to do anything. Your coverage continues automatically into the new year. However, you should still review the Annual Notice of Change to make sure there are no surprises — sometimes plans make changes you'll want to know about even if you stay.

What if my doctor leaves my plan's network?

This is a may have access to Life Event that may let you change plans outside of Annual Enrollment Period. Contact your insurance company or call 1-800-MEDICARE to report the change and ask whether you're may be able to access to switch. You'll typically have 60 days from when you learn your doctor left the network.

Can I get help choosing a plan if I'm confused?

Yes. Call 1-800-MEDICARE to speak with a representative, or contact your State Health Insurance information Program (SHIP) for free, one-on-one counseling. SHIP counselors are trained specifically to help Medicare beneficiaries understand their options and are not affiliated with any insurance company.