You can change Medicare Advantage plans during specific windows each year, not whenever you want

Medicare Advantage plans lock you in for the calendar year. Once you pick a plan on or before December 7, it becomes your coverage starting January 1, and you cannot switch to a different Advantage plan until the next open period arrives — with a few exceptions for people in specific situations. The main windows are the Annual Enrollment Period (October 15 to December 7 each year) and the Medicare Advantage Open Enrollment Period (January 1 to March 31). If you miss both and do not fall into an exception category, you are stuck with your current plan until the following October.

The rules exist because Medicare Advantage plans are run by insurance companies, not by Medicare itself. Each plan sets its own network of doctors, its own drug formulary, and its own out-of-pocket costs. Allowing people to switch constantly would make it impossible for plans to manage their costs or predict their membership. Understanding when you can move and what counts as a valid reason matters because the wrong timing can cost you weeks without coverage or lock you into a plan you did not want.

Key Takeaways

  • The Annual Enrollment Period runs October 15 to December 7 each year, and any Medicare Advantage member can switch plans during this window with no questions asked.
  • The Medicare Advantage Open Enrollment Period (January 1 to March 31) lets you switch once per year, but only if you are already enrolled in a Medicare Advantage plan on January 1.
  • Certain life events — moving out of your plan's service area, losing employer coverage, or becoming may be able to access for Medicaid — may let you switch outside the regular windows.
  • If you switch plans, your new coverage starts on the first day of the following month, so timing your switch matters if you have upcoming medical appointments or prescriptions.
  • You must contact your new plan directly or use Medicare.gov to make the switch; your old plan does not handle the transfer.

The Annual Enrollment Period: October 15 to December 7

This is the main window when any Medicare beneficiary can change plans, and it is the easiest time to switch. You do not need a reason, do not need to prove anything, and do not need permission from Medicare or your current plan. You can move from one Medicare Advantage plan to another, or from Medicare Advantage to Original Medicare with a Medigap or Part D plan. The important date is December 7 at 11:59 p.m. Eastern time if you enroll online or by phone; if you mail a paper form, it must be postmarked by December 7.

Your new coverage starts January 1 of the following year. This means if you switch on November 1, you have two months of your old plan still active. If you have a surgery scheduled for December or take a medication you need to refill before the year ends, check whether your current plan or your new plan covers it — you may need to time your switch differently or arrange a bridge prescription from your pharmacy.

During this period, you can also switch from Original Medicare to Medicare Advantage if you have not been in an Advantage plan before, or if you left one more than one year ago. People new to Medicare or returning to Advantage after a gap have the same open window as everyone else.

The Medicare Advantage Open Enrollment Period: January 1 to March 31

This window is shorter and has a key restriction: you can only use it if you are already enrolled in a Medicare Advantage plan on January 1. It lets you switch to a different Medicare Advantage plan once during the first three months of the year. You cannot use this period to switch from Medicare Advantage to Original Medicare — that requires the Annual Enrollment Period.

Your new coverage starts the first day of the month after you enroll. If you switch on January 15, your new plan begins February 1. If you switch on March 20, your new plan begins April 1. This matters if you take monthly medications or have standing appointments; call your new plan before you switch to confirm they have your doctors in network and your drugs on their formulary.

This period exists because people sometimes discover in January that their plan has dropped their doctor, raised their costs, or changed their drug coverage in ways that affect them. It gives you one chance to move without waiting until October. You can use it only once per year, so if you switch in February, you cannot switch again until the following January 1.

Life Events That Let You Switch Outside Regular Windows

Certain situations create a Special Enrollment Period that lets you change plans outside the normal windows. These are called "may have access to events" and Medicare has specific definitions for each one. The most common are: you move out of your plan's service area; you lose employer-sponsored health coverage; you become newly may be able to access for Medicaid or lose Medicaid coverage; you are released from incarceration; or your plan leaves the Medicare program entirely.

If your plan announces it is leaving Medicare, you will receive a notice from Medicare and your plan. You then have until the date the plan closes to switch to another plan. This is not a choice — your coverage will end on that date if you do not move. Medicare will send you a list of plans available in your area and instructions for switching.

If you move to a new state or a new county and your current plan does not serve that area, you have 60 days from the date you move to switch to a plan that does cover your new location. You will need to show proof of your move — a utility bill, lease, or change of address from the post office usually works. Call Medicare at 1-800-MEDICARE to report the move and ask what counts as proof in your situation.

If you lose health coverage through an employer or union, you have 60 days from the date coverage ends to switch plans. This includes losing coverage because you retired, were laid off, or your employer dropped the plan. You will need a letter from your employer or former employer stating the date coverage ended.

What Happens If You Miss All the Windows

If you do not switch during the Annual Enrollment Period (October 15 to December 7) or the Medicare Advantage Open Enrollment Period (January 1 to March 31), and you do not have a may have access to life event, you cannot change plans until the next October 15. This applies even if you discover your doctor left the network in April, your plan raised your copay in June, or a new plan launches in September that would be better for you.

The only exception is if your plan itself leaves Medicare or stops serving your area. In that case, Medicare will contact you and give you a important date to switch. You do not have to do anything except pick a new plan by that date.

If you are locked in and unhappy, document what went wrong — which doctor left, what the new costs are, which drugs are no longer covered. When October arrives, you will have concrete information to use when comparing plans for the next year.

How to Switch Plans: The Steps and Timeline

You have three ways to switch: online at Medicare.gov, by phone at 1-800-MEDICARE, or through a licensed insurance agent. You do not contact your current plan to leave — you contact your new plan to join, or you use Medicare.gov to enroll. Your current plan will be notified automatically by Medicare once your new enrollment is processed.

If you enroll online at Medicare.gov during the Annual Enrollment Period, your switch is usually confirmed within one business day. If you call Medicare or an agent, confirmation takes longer — sometimes several days. If you use a paper form mailed to Medicare, allow at least two weeks for processing. Do not wait until December 6 to mail a form; use the phone or online option instead.

Before you switch, write down the name and phone number of your new plan's customer service line. Call them after your enrollment is confirmed to verify they have your doctors in network, your pharmacy in network, and your current medications on their formulary. Ask whether you need to do anything to transfer your medical records or whether the plan will request them automatically. If you take a medication that requires prior authorization, ask whether your new plan will honor the authorization from your old plan or whether you need a new one.

What to Watch For When Comparing Plans

When you are in a window to switch, Medicare.gov has a tool called "Compare Care Plans" that shows you plans available in your zip code. Enter your current doctors and pharmacies to see which plans include them. Check the monthly premium, the annual deductible, the copay amounts for office visits and specialists, and whether your current drugs are on the plan's formulary. Some plans have $0 premiums but high copays; others charge a monthly fee but have lower out-of-pocket costs. The cheapest plan is not always the best plan for your situation.

Pay special attention to whether your plan covers services you use regularly. If you see a cardiologist four times a year, a plan with a $50 specialist copay costs you $200 per year just for those visits. If you take three prescription drugs, check whether all three are covered and at what tier — a drug on Tier 4 costs more than one on Tier 1. If you use a specific pharmacy, confirm it is in network; some plans have limited pharmacy networks.

Read the plan's "Summary of Benefits and Coverage" document, which is a standardized form that shows what the plan covers and what you pay. It is dense, but it is the only place you will find the full picture. Do not rely on the plan's marketing materials or website alone.

Frequently Asked Questions

Can I switch Medicare Advantage plans if my doctor left the network?

Only during the Annual Enrollment Period (October 15 to December 7) or the Medicare Advantage Open Enrollment Period (January 1 to March 31). If your doctor leaves in April, you cannot switch until October unless your plan itself is leaving Medicare. Some plans allow you to request a continuity-of-care exception that lets you see the doctor outside the network for a limited time, but this is not a may provide and varies by plan.

What if I switch plans and then change my mind?

You have one chance to undo a switch during the Annual Enrollment Period. If you enroll in a new plan between October 15 and December 7, you can disenroll and go back to your old plan if you do this before December 31. After December 31, your switch is final and you cannot go back until the next enrollment period. During the Medicare Advantage Open Enrollment Period (January 1 to March 31), you cannot undo a switch once it is processed.

Do I lose coverage if I switch plans in the middle of the month?

No. Your old plan stays active until the last day of the month you switch. Your new plan starts on the first day of the following month. There is no gap in coverage. If you switch on January 15, you have Medicare Advantage coverage from your old plan through January 31 and from your new plan starting February 1.

Can I switch from Medicare Advantage to Original Medicare outside the enrollment periods?

Only if you have a may have access to life event, such as moving out of your plan's service area or losing employer coverage. Otherwise, you must wait for the Annual Enrollment Period (October 15 to December 7). The Medicare Advantage Open Enrollment Period does not let you switch to Original Medicare — it only lets you switch between Medicare Advantage plans.

What should I ask my new plan before the switch takes effect?

Confirm that your current doctors are in network, your pharmacy is in network, and your medications are on the formulary. Ask whether you need to do anything to transfer medical records or whether the plan requests them automatically. If any of your drugs require prior authorization, ask whether your new plan will honor your old plan's authorization or whether you need a new one. Get the plan's customer service phone number and ask about their hours and wait times.