Medicare, the federal health insurance program for people aged 65 or older and certain younger individuals with disabilities, is structured around four main components: Part A, Part B, Part C (Medicare Advantage), and Part D (prescription drug coverage). Unlike standard private insurance, beneficiaries cannot switch plans or coverage options at any time they choose. The ability to make changes is strictly confined to specific, limited enrollment windows designated by the government. You must pay close attention to the calendar to adjust your health and drug coverage.
The Standard Annual Enrollment Period
The most recognized opportunity for changing Medicare coverage is the Annual Enrollment Period (AEP), which occurs every fall. This fixed window runs from October 15 through December 7 each year, allowing all Medicare beneficiaries a chance to review their current coverage. Any changes made during this time frame will become effective on January 1 of the following year.
During this period, you can make significant adjustments to your health and drug plans. You can switch from Original Medicare (Parts A and B) to a Medicare Advantage plan (Part C), or change from a Medicare Advantage plan back to Original Medicare. It is also the time to change between different Medicare Advantage plans, with or without prescription drug coverage. Finally, the AEP allows you to join, drop, or switch a standalone Medicare Part D prescription drug plan.
Beneficiaries often use this time because Medicare Advantage and Part D plans are offered by private insurance companies, and the plans’ costs, benefits, and covered drugs can change annually. It is important to submit your enrollment request by the December 7 deadline to guarantee your new coverage begins on January 1.
Enrollment Periods for Medicare Advantage Plans
The Medicare Advantage Open Enrollment Period (MA OEP) is specifically for individuals who are already enrolled in a Medicare Advantage plan. This period occurs annually from January 1 through March 31. The MA OEP provides a second opportunity to make a single change to your coverage early in the year.
This window allows you to switch from your current Medicare Advantage plan to a different Medicare Advantage plan, with or without drug coverage. Alternatively, you can drop your Medicare Advantage plan entirely and return to Original Medicare (Parts A and B). If you return to Original Medicare, you are also permitted to enroll in a stand-alone Medicare Part D prescription drug plan during this time.
A key difference is the limitation on use; you can only make one change during the MA OEP. This period is intended for those who enrolled in a Medicare Advantage plan during the AEP but found that the plan does not meet their needs. The change you select will take effect on the first day of the month following the month the plan receives your request.
Life Events That Trigger Special Enrollment
Beyond the fixed calendar periods, Medicare offers Special Enrollment Periods (SEPs) that allow beneficiaries to make changes outside of the standard windows due to specific life circumstances. SEPs function as exceptions to the general enrollment rules, recognizing that certain events can significantly impact a person’s health coverage needs. Eligibility is determined on a case-by-case basis.
One common qualifying event is moving to a new address that is outside of your current plan’s service area. If this happens, you typically have a two-month SEP to enroll in a new Medicare Advantage or Part D plan available in your new location.
Another trigger is losing other creditable coverage, such as employer-sponsored health insurance. If you were working past age 65 and delayed enrollment, you may have an eight-month SEP to enroll in Medicare Parts A and B after your employer coverage ends.
Other events that can trigger an SEP include qualifying for the Low-Income Subsidy, also known as Extra Help, which assists with Part D costs. A plan may also trigger an SEP if it leaves the Medicare program, stops serving your area, or significantly reduces its provider network. For most of these life events, the SEP is time-sensitive, often granting a 60-day window from the date of the qualifying event to make the necessary changes.