When Does Medicare Part D Start? 
You must enroll in Part D when you turn 65 or qualify for Medicare . You have the three months before , the month of , and three months after you turn 65 to enroll in a plan . The plans are administered through private insurance companies under the supervision of Medicare . If you fail to enroll when you are eligible you will be penalized by Medicare for each month you do not have creditable coverage . You may enroll in a plan or change your plan each year from October 15th through December 7th . 