Not everyone knows this, but each year Medicare Advantage plan members can change plans after December 31. There are two major, yearly recurring enrollment windows for Medicare beneficiaries: Annual Enrollment (Oct15-Dec7) and Open Enrollment (Jan1-Mar31).
Annual Enrollment Period (AEP)
Most people are familiar with Medicare’s Annual Enrollment Period (AEP) from October 15th to December 7th. In October, insurance companies and brokers release information for new Medicare Advantage plans for the coming year. Marketing to Medicare beneficiaries begins as well. This includes LOTS of commercials, LOTS of mail sent, and for many, LOTS of phone calls received. During Annual Enrollment, people without a Medicare Advantage plan (MA) or Prescription Drug Plan (PDP) can opt in and join one if eligible.
People who already have MA and PDP plans can change to a new plan during AEP. Someone enrolled in a Medicare Advantage (MA) plan who wishes to return to Original Medicare and move to a PDP rather than an MA plan may do so during this time. In fact, a new plan can be selected multiple times during AEP. The last plan selected will cancel all previous enrollments and become the enrollee’s plan for the coming year, effective Jan 1st. Since plan benefits and terms change every year, it’s an important time to review and select a plan for the coming year. But plan selection options don’t end there.
Open Enrollment Period (OEP)
When the new plan starts or previous plan renews with new terms on Jan 1st, the Open Enrollment Period (OEP) also begins. This enrollment window offers a single enrollment option from Jan 1st to March 31st each year. During this time, only those with an active MA or PDP plan can make a plan change, which becomes effective the first of the next month.
Essentially, this enrollment window allows enrollees to try out their new plan. They can identify any concerns with network providers or prescription drug coverage and make a change if needed. During this time, restrictions on marketing mean not as many beneficiaries know this enrollment window exists. Someone enrolled in a Medicare Advantage (MA) plan who wishes to return to Original Medicare and move to a PDP rather than an MA plan may do so during this time.
Alternative Names
It would be nice if the enrollment periods had more universally applied names. Unfortunately, these two distinct enrollment windows’ NAMES, i.e. Open or Annual, are sometimes used interchangeably. The Medicare.gov website refers to the Annual Enrollment Period (Oct15-Dec7) as Open Enrollment. It refers to the Open Enrollment Period (Jan1-Mar31) as Medicare Advantage Open Enrollment. However among insurance companies and brokers, the names “Annual” and “Open” used in this article are standard.
The most important takeaway is knowing that there are TWO DISTINCT enrollment windows for MA and PDP enrollees to use. As always, we are here to help you compare and select the Medicare plan that works best for YOU. Use this form to request an appointment with us!

