One of the most common questions we hear at CIENEL is: "When can I change my Medicare plan?" The answer depends on which enrollment period applies to you. Medicare has specific windows during the year — and acting outside those windows can mean staying stuck with a plan that no longer fits your life.
There are three main periods you need to know: the Annual Enrollment Period (AEP), the Open Enrollment Period (OEP), and Special Enrollment Periods (SEPs). Each one has different rules about what changes you can make.
AEP — Annual Enrollment Period (October 15 – December 7)
The AEP is the most important enrollment window of the year. It runs from October 15 to December 7, and during that time any Medicare beneficiary can switch from Original Medicare to Medicare Advantage, switch from Medicare Advantage back to Original Medicare, change from one Advantage plan to another, or change their prescription drug plan (Part D).
Changes you make during the AEP take effect on January 1 of the following year. This is the ideal time to review your coverage with your agent — check whether your current plan still works for your doctors and medications, and make adjustments before the new benefit year begins.
OEP — Open Enrollment Period (January 1 – March 31)
The OEP applies exclusively to people already enrolled in a Medicare Advantage plan. During this window — January 1 through March 31 — you can switch to a different Advantage plan or return to Original Medicare (with or without Part D drug coverage).
What you cannot do during the OEP: switch from Original Medicare to Medicare Advantage, or change a standalone Part D plan if you are on Original Medicare. The OEP is a narrower window than the AEP, designed specifically for people who already have Advantage and need to make an adjustment.
SEP — Special Enrollment Period (life events)
SEPs are enrollment windows that open when a specific life event occurs outside the regular calendar. Some examples of events that can trigger a SEP: moving to an area where your current plan does not operate, losing coverage from an employer plan, qualifying for Medicaid or a Low Income Subsidy (LIS), or being discharged from a long-term care facility.
The length of a SEP varies by event type — typically two to three months. It is important to act quickly when a qualifying event happens, because the window can close before you realize it.
How to make the most of these windows
The best time to review your coverage is before the AEP begins — ideally in September or October, when plans release their information for the coming year. That gives you time to compare what is changing in your current plan: drug formulary, provider network, copays.
If you are not sure which period you are in or what changes you are allowed to make, a licensed agent can review your situation at no cost and no obligation. At CIENEL we walk our clients through every enrollment period to make sure they always have the coverage that best fits their life.