When Can I Get Medicare Part D? 
You can sign up for Medicare Part D when you first are enrolled in Medicare Part A and B . This is at age 65 , if you are receiving Social Security at age 65 . Or it can be at a younger age , if you have been receiving SSDI for two years or have ESRD or ALS . If you enrolled in Part B after Part A , in the open enrollment period , you can enroll in Part D from April 1 to June 30 . 