Medicare Annual Enrollment Period runs from October 15 to 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. It always starts on October 15 and ends on December 7. Any changes you make during this window take effect on January 1 of the following year.

If you miss this window, you cannot switch plans until the next October 15 — unless a life event like moving, losing employer coverage, or a death in your household opens a Special Enrollment Period just for you. Missing the important date can lock you into a plan you no longer want for a full year.

The enrollment period is the same across all states and all Medicare plans. It does not matter whether you have Original Medicare, a Medicare Advantage plan, or a Medigap policy — the dates are fixed.

Key Takeaways

  • Annual Enrollment Period is October 15 through December 7 each year, and changes take effect January 1.
  • You can switch from Original Medicare to Medicare Advantage, from Medicare Advantage to Original Medicare, or change to a different plan in the same category.
  • If you miss the October 15 important date, you cannot change plans until the following October unless a may have access to life event occurs.
  • You should review your current plan each year because drug formularies, provider networks, and premiums change annually.
  • Medicare.gov, your plan's website, or a State Health Insurance information Program (SHIP) counselor can help you compare options at no cost.

What you can change during Annual Enrollment Period

During AEP, you can switch between any Medicare plans available in your area. The main moves are: switching from Original Medicare to a Medicare Advantage plan, switching from Medicare Advantage back to Original Medicare, or changing to a different Medicare Advantage plan or Medigap policy.

You can also add or drop prescription drug coverage (Part D) if you have Original Medicare, or switch to a different Part D plan. If you are on a Medicare Advantage plan that includes drug coverage, you can switch to a different Advantage plan with different drug coverage, or drop the Advantage plan and go back to Original Medicare with a separate Part D plan.

You cannot, however, make changes outside of AEP unless you have a may have access to event. may have access to events include turning 65, losing employer coverage, moving to a new state, getting married or divorced, or experiencing a death in your household. These events open a Special Enrollment Period lasting 60 days from the date of the event.

Why you should review your plan each year

Even if you are happy with your current plan, the details change every year. Insurance companies update their drug formularies (the list of medications they cover), change which doctors and hospitals are in their network, and adjust premiums and out-of-pocket costs. A plan that was affordable last year might cost more this year, or a medication you take might move to a higher cost tier.

Reviewing your plan during AEP takes a few hours but can save you hundreds of dollars annually. You should check whether your doctors and pharmacy are still in-network, whether your medications are still covered at the same cost, and what the new premiums and deductibles will be.

If you do nothing during AEP, you automatically stay in your current plan. This is called "passive renewal." Many people assume they are locked in, but that is not true — you have the right to change, and the window is open for seven weeks each fall.

How to compare plans and make a change

Start by visiting Medicare.gov and using the Plan Finder tool. You will need your ZIP code, a list of your current medications, and the names of your doctors and preferred pharmacy. The tool shows you all plans available in your area, their costs, and which doctors and pharmacies are in-network.

You can also call your current plan directly or contact the plans you are considering. Most plans have customer service lines that can walk you through coverage details. If you want help from someone who is not selling a plan, contact your State Health Insurance information Program (SHIP). SHIP counselors are free, trained, and unbiased. You can find your state's SHIP by calling 1-800-MEDICARE or visiting Medicare.gov.

Once you have decided on a new plan, you can enroll in three ways: online through Medicare.gov, by phone at 1-800-MEDICARE, or by mail using the enrollment form your plan sends you. Online enrollment is usually fastest and takes about 15 minutes.

Important dates and important date

The Annual Enrollment Period is October 15 through December 7. Plans must receive your enrollment by December 7 for coverage to start on January 1. If you enroll after December 7, your coverage will not begin until the first of the following month.

If you are turning 65 and enrolling in Medicare for the first time, you have a different window called the Initial Enrollment Period. It runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. Missing this window can result in permanent penalties on your premiums.

If you experience a may have access to life event outside of AEP, you have 60 days from the date of the event to make changes. You will need to provide proof of the event — such as a marriage certificate, divorce decree, or notice of loss of coverage — when you enroll.

What happens if you miss the important date

If you do not make a change by December 7, you stay in your current plan for the entire following year. You cannot switch plans again until the next October 15, even if your plan changes its coverage, raises its premiums, or your doctor leaves the network.

The only exception is if you experience a may have access to life event. Moving to a new state, losing employer coverage, getting married or divorced, or having a death in your household all open a 60-day Special Enrollment Period. You will need to contact Medicare or your plan within 60 days of the event and provide documentation.

If you miss both AEP and the important date for a may have access to event, you are stuck until the following October. This is why setting a calendar reminder in early October is worth the two minutes it takes.

Getting help with your decision

If you are unsure which plan is right for you, several free resources can help. Your State Health Insurance information Program (SHIP) offers one-on-one counseling by phone or in person. SHIP counselors have no financial stake in which plan you choose and can explain the differences in plain language.

Medicare.gov has a Plan Finder tool and comparison charts. You can also call 1-800-MEDICARE to speak with a Medicare representative who can answer questions about coverage and help you understand your options. If you are already enrolled in a plan, that plan's customer service line can answer questions about your specific coverage.

Some community centers, senior centers, and libraries offer free Medicare counseling sessions during the fall. Your local Area Agency on Aging can tell you whether sessions are available in your area.

Frequently Asked Questions

Can I change plans more than once during Annual Enrollment Period?

Yes. You can enroll in a new plan, then change your mind and enroll in a different plan before December 7. Only your last enrollment counts. However, switching multiple times can be confusing, so it is better to make your decision carefully the first time.

What if I enroll in a new plan but want to go back to my old one?

If you change your mind after December 7, you cannot switch back until the next October 15 unless you have a may have access to life event. This is why it is important to compare plans carefully before you enroll and make sure you are comfortable with your choice.

Do I have to enroll in a plan during Annual Enrollment Period?

No. If you are happy with your current plan, you can do nothing and stay enrolled. Your coverage continues automatically on January 1. You only need to act if you want to change plans.

What if my doctor or pharmacy is no longer in my plan's network?

This is a common reason to switch plans during AEP. Check the new plan's network before you enroll to make sure your doctor and pharmacy are included. If you cannot find a plan that includes all your providers, contact your current plan to ask whether they will make an exception or whether your doctor is still covered under different terms.

Can I switch plans if I have a pre-existing condition?

Yes. Medicare cannot deny you coverage or charge you more because of a pre-existing condition. You can switch to any plan available in your area during AEP without any restrictions based on your health history.