Fall Open Enrollment, also known as the Annual Coordinated Election Period, is the span of time from October 15 through December 7. During this period you can change your Medicare private drug plan (Part D) and/or your Medicare health plan choice (Original Medicare or a Medicare Advantage plan) for the following year. This is also the time you can enroll in Part D for the first time if you did not enroll during your Initial Enrollment Period. (You may have to pay a premium penalty if you enroll during this time unless you have had other creditable coverage.) Your new coverage will begin January 1.