Changing Medicare Advantage Plans During AEP: What Changes on January 1 and What Stays the Same

Many people think about a new Medicare Advantage plan in the fall and then worry. Will I lose my Part B? Will I have a gap with no cover? This guide walks through what changes on January 1 when you switch, and what stays the same. Our Medicare Advantage section holds the hub for this group of guides.

How a switch works

You join the new plan in the fall window. Medicare sets your new plan to start on January 1. Your old plan ends on December 31. There is no gap day if the switch is done in the window and on time.

You do not have to tell the old plan. Joining the new plan ends the old one. Keep the letter that confirms your new plan, with the start date on it.

If you join more than one plan in the window, the last one Medicare gets is the one that counts. So make your last choice your final choice.

What changes on January 1

None of these change in the middle of the fall. They change on the start date, January 1, 2027 (Ledger B4).

• Your plan card: you get a new card from the new plan. The old card stops working.
• Your copays: each plan sets its own costs for visits, stays, and drugs.
• Your network: you must use doctors in the new plan network for the best cost.
• Your drug list: the new plan list rules your drugs from January 1.
• Your extra perks: dental, vision, or hearing help can differ by plan.
• Your yearly limit: the new plan cap on your costs takes over.

What stays the same

Your Part B stays in place. You keep paying the Part B premium. In 2026 that standard premium is $202.90 a month (Ledger A1). A switch does not pause it and does not end it.

Your Medicare number stays the same. Your right to Medicare stays the same. If you have Medicaid help or Extra Help, ask how a switch may affect it before you join. Those helps can stay, but the plan must be one that works with them.

Your care does not have to start over. You can take your records and drug list to the new plan doctors. Ask the new plan how to move ongoing care, such as therapy or a planned test.

Our guide on switching back to Original Medicare and trial rights explains the right some people hold to undo a first choice. Our star ratings guide shows one way to weigh plan quality.

Who pays for what

• Medicare pays your new plan each month from January 1 to cover your care.
• Your new plan pays for covered care under its copays, network, and yearly limit.
• You pay the Part B premium of $202.90 a month in 2026 (Ledger A1), plus any plan premium and copays.
• Original Medicare pays nothing while you are in a Medicare Advantage plan.
• Medicaid can help some people with premiums and costs if they qualify through their state.
• Private pay covers care outside plan rules and care the plan does not cover.

Sample situation

James is 68. His plan will drop his heart doctor in January. In November he finds a plan that keeps that doctor and covers his drugs. He joins it before December 7, 2026 (Ledger B4). His old plan runs through December 31. His new plan starts January 1, 2027 (Ledger B4). He keeps paying his Part B premium of $202.90 a month, the 2026 amount (Ledger A1). In late December his new card comes. He brings it and his drug list to his first visit in January. He had no day with no cover, and he kept the doctor who knows his case best.

The window after January

If you are in a Medicare Advantage plan on January 1, one more window opens. The Medicare Advantage Open Enrollment Period runs from January 1 to March 31, 2027 (Ledger B5). It is for people who are in a Medicare Advantage plan only. In it you can switch to a new Medicare Advantage plan or go back to Original Medicare one time.

This window does not help people who stayed in Original Medicare in the fall. It is not a second fall window for all. Know which group you are in.

Mistakes that cause stress in January

The most common mistake is to shop by premium alone. A plan with no added premium can still cost more for the care you use. A hospital copay, a drug tier, or a lost doctor can outweigh a small premium saving in one visit.

A second mistake is to check this year's plan book for next year's care. Networks and drug lists are set by year. Always use the list for the year the new plan will run.

A third mistake is to wait until late December. At that point the fall window has closed. If your form has an error, you may have no time to fix it. Join early in the window when you can, and keep the confirmation letter.

A fourth mistake is to cancel other cover too soon. Do not drop a drug plan or other cover until you know the new plan start date in writing. Your old Medicare Advantage plan ends on its own when the new one starts, but other cover can work in other ways.

Last, tell your doctors and pharmacy about the switch at your first visit in January. Bring the new card. Old cards on file cause billing errors that take weeks to sort out, even when the switch itself was clean and on time.

Steps to switch with care

• List your doctors, hospital, and drugs first.
• Check each one in the new plan for next year, not this year.
• Add up premiums and the costs for care you know you will use.
• Join before December 7 and keep proof of the date.
• In January, show your new card at each visit and at the pharmacy.

Sources

• https://www.medicare.gov/health-drug-plans/open-enrollment
• https://www.medicare.gov/basics/costs