If you realize you missed an earlier deadline, check your Special Enrollment Period eligibility before assuming the General Enrollment Period is your only option. Medicare’s annual Open Enrollment Period runs from October 15 through December 7, when beneficiaries can make changes such as switching Medicare Advantage plans, moving between Original Medicare and Medicare Advantage, or changing Medicare drug plans. The Medicare Advantage Open Enrollment Period applies to people already enrolled in a Medicare Advantage plan and allows them to switch to another Medicare Advantage plan or return to Original Medicare, with the ability to join a separate drug plan when returning to Original Medicare. New Medicare Advantage enrollees may also have an opportunity to make a change during the first three months they have Medicare. If you miss your Initial Enrollment Period and aren’t eligible for a Special Enrollment Period, you may need to use Medicare’s General Enrollment Period, which runs from January 1 through March 31 each year.