When Can You Switch Medicare D Plans? 
You can only change your Medicare Part D prescription drug plan during the annual enrollment period - October 15th to December 7th of each year . If/When you change your part D plan to another part D plan , the effective date becomes January 1 of the following year . To secure a new part D plan outside of the annual enrollment period , you will need a special enrollment period , have Medicare and Medicaid , or be eligible for medicaid and/or a low income subsidy . You can look on medicare.gov to see more information regarding changing part D coverage . 