To switch to Medicare Advantage, you must have Part A and Part B, live in the plan’s service area, and join during an enrollment period that applies to you. Compare the plan’s doctors, drug coverage, and total costs before enrolling.

When Can You Join?

Common opportunities include:

  • Your Initial Enrollment Period when first eligible for Medicare
  • Medicare Open Enrollment from October 15 through December 7, with coverage starting January 1
  • A Special Enrollment Period after certain moves, coverage losses, or other qualifying events

The January 1–March 31 Medicare Advantage Open Enrollment Period is only for people already in Medicare Advantage. A person in Original Medicare cannot use it to join an Advantage plan.

Check Eligibility and Plan Details

You need Part A and Part B, must continue paying the Part B premium, and generally must live in the plan's service area.

Before enrolling, confirm:

  • Each doctor, hospital, and facility you use is in-network
  • Your drugs are on the formulary, the plan’s list of covered drugs, and its coverage rules work for you
  • Your preferred pharmacies are in-network
  • Copayments, deductibles, and the out-of-pocket limit fit your budget
  • Rules for specialist referrals, approval before care, travel, and extra benefits work for you

Call both the plan and important providers. Directory information can change.

What Happens to Other Coverage?

You cannot use Medigap to pay your share of Medicare Advantage costs. If you already have Medigap, ask whether a specific first-year trial right would let you get it back and what its deadline is. Get that answer before deciding to cancel; a later return is not always guaranteed. Joining Medicare Advantage may also affect employer or union benefits.

Joining an Advantage plan with drug coverage normally replaces a stand-alone Part D plan. Confirm when the new drug coverage starts and the old plan ends. You can use a separate Part D plan with certain other Advantage plans, such as a Medicare Medical Savings Account (MSA) plan or a Private Fee-for-Service (PFFS) plan without drug coverage. Check your plan type. Medicare’s joining-a-plan guidance.

After enrollment, save the plan name and ID, start date, and confirmation number. Check which card to use for prescriptions on the first day, and tell providers about any appointment or authorization that spans the coverage change.

Medicare policy sources last checked: October 8, 2026.