Medicare part b benefits - who is eligible.

How You Get Part B

• If you get benefits from Social Security or the Railroad Retirement Board (RRB), in most cases you'll automatically get Part B starting the first day of the month you turn 65. If your birthday is on the first day of the month, your Part B will start the first day of the prior month. 
• If you're under 65 and disabled, you'll automatically get Part B after you get disability benefits from Social Security or certain disability benefits from the RRB for 24 months. You’ll get your Medicare card in the mail about 3 months before your 65th birthday or your 25th month of disability.
• If you don't want Part B, follow the instructions that come with the card, and send the card back. If you keep the card, you keep Part B and will pay Part B premiums.
• If you have ALS (Amyotrophic Lateral Sclerosis, also called Lou Gehrig’s disease), you automatically get Part B the month your disability benefits begin.