Final answer:
Medicare beneficiaries can switch from a Part D plan to a MAPD plan during the Annual Enrollment Period from October 15 to December 7 each year.
Step-by-step explanation:
Medicare beneficiaries have specific periods during the year in which they can make changes to their coverage. The Annual Enrollment Period is from October 15 to December 7 each year.
During this time, beneficiaries can switch from a standalone Part D prescription drug plan to a Medicare Advantage Prescription Drug (MAPD) plan if they wish to have prescription drug coverage included with their Medicare Advantage plan.
It's important to note that changes made during this period take effect on January 1 of the following year.