Can I Enroll In Medicare Part D Anytime? 
As a rule no , you can enroll in Part D when you first become eligible , during the Anual Election Period , or if you have a Special qualifying event such as losing your group coverage or the plan pulls out of the area , or you move out of the service area . If you qualify for Extra Help with your drugs from Medicare or if you are also on Medicaid you can swithch whenever you want . 