Beginning January 1, 2019, a Medicare Advantage Open Enrollment Period (MA OEP) will run from January 1 to March 31 each year. This replaces the old Medicare Advantage Disenrollment Period, which ran from January 1 to February 14.
If you are already enrolled in a Medicare Advantage plan (Part C) on January 1, you can disenroll from your current plan and sign up for a different Advantage plan during the new Medicare Advantage Open Enrollment Period (MA OEP). You may do this only once.
During this time, you can also drop your Medicare Advantage plan and return to Original Medicare (Parts A & B), at which point you could add a Medicare Supplement (Medigap) plan or Prescription Drug Plan (Part D).