When To Enroll In Part B Medicare? 
Most people will automatically be enrolled in Medicare Part B at the same time they are enrolled in Medicare Part A . They will receive their Medicare card in the mail three months before their 65th birthday or in the 25th month of their disability . If you or your spouse is working at a job with over 20 employees where the group health insurance provided is your primary carrier , you may delay enrolling in Part B. Call the Social Security Administration at 800-772-1213 to discuss before delaying or turning down enrollment in Medicare Part B . 