Every year from October 15 through December 7, Medicare beneficiaries can make changes to their coverage for the coming year. Changes take effect January 1. Most people do nothing during this window. That is not always the wrong choice — but it should be a deliberate decision, not a default. Here is what the Annual Enrollment Period (AEP) allows, what to actually compare, and how to know when switching is worth the effort.
During the AEP, any Medicare beneficiary can take any of the following actions without restriction: switch from Original Medicare to a Medicare Advantage (MA) plan, switch from one MA plan to a different MA plan, switch from MA back to Original Medicare, enroll in a new Part D prescription drug plan, switch from one Part D plan to another, or drop Part D coverage entirely (though this triggers a penalty unless you have other creditable coverage). There is also a separate window: the Medicare Advantage Open Enrollment Period (MA OEP) runs from January 1 through March 31. This period is available only to people already enrolled in an MA plan. It allows one plan change — either to a different MA plan or back to Original Medicare — but it does not allow switching from Original Medicare into MA, and it does not allow standalone Part D changes for people on Original Medicare. Enrollment Period When Who Can Use What It Allows** It** Annual Enrollment Oct 15 Dec Any Medicare Any plan change; Period (AEP) 7 beneficiary takes effect Jan 1 MA Open Enrollment Jan 1 Mar MA plan enrollees Switch MA plans or Period (MA OEP) 31 only return to Original Medicare; one change only Special Enrollment Triggered by Those with Varies by event Period (SEP) qualifying qualifying life type event change 5-Star Special Any time Any beneficiary Join a 5-star Enrollment with a 5-star rated plan once plan available per year
The AEP generates a flood of marketing materials. Most of them lead with the premium. Premium is one input. It is not the primary one. The maximum out-of-pocket (MOOP) limit is the ceiling on how much you can spend in a year on covered services under a Medicare Advantage plan. In 2026, the federal maximum is $9,350 for in-network services. Plans set their own limits below this cap. A plan with a $0 monthly premium and a $9,350 MOOP is not automatically a better deal than a plan with a $60 monthly premium and a $4,500 MOOP — especially if you have recurring medical needs. The math requires comparing expected utilization against each plan's cost-sharing structure. Network access is the second major variable. Medicare Advantage plans use restricted networks. The hospital your cardiologist operates at, the specialist you have seen for five years, the cancer center two counties over — none of these are guaranteed to be in-network. Networks change annually. A provider who was in-network in December may not be in-network in January. The AEP period — before a plan changes take effect — is the time to verify, not assume. Drug formulary alignment is the third factor. If you take maintenance medications, pull the plan's formulary before switching and confirm your specific drugs are covered at the tier level you expect. A drug moving from Tier 2 to Tier 4 on a formulary can increase your annual drug cost by hundreds of dollars even if the plan's premium is lower. CMS star ratings are the fourth variable worth checking. The Centers for Medicare and Medicaid Services (CMS) rates Medicare Advantage and Part D plans annually on a 1-to-5 star scale based on clinical quality, member satisfaction, and customer service performance. Plans rated 5 stars have an additional benefit: they can be joined at any time during the year, not just during AEP. This creates flexibility for people who discover a quality issue with their current plan mid-year.
The case for not switching is real. Changing Medicare Advantage plans mid-relationship resets your relationship with the network. If you have a complex chronic condition being managed by a specialist you trust, confirming that specialist remains in-network under your current plan and comparing that against a new plan's network may strongly favor staying. Drug formularies can also favor continuity. If your current plan covers all your medications at favorable tiers, a plan switch that saves $30 per month on premium but costs $80 per month in higher drug tiers is a net loss.
There are three situations where evaluating a switch is worth the time. First, if your plan's star rating has dropped significantly — to 2 or fewer stars — that is a quality signal worth taking seriously. Second, if your network has changed and providers you rely on are no longer in-network, you have effectively been involuntarily switched to a less favorable coverage situation without a plan change. Third, if your medication list has changed, a formulary comparison against competing plans may reveal meaningfully better drug coverage elsewhere.
CMS publishes its Medicare plan star ratings annually. A Medicare|Advantage or Part D plan with a 5-star rating can be joined at any