If you already receive Social Security or Railroad Retirement Board (RRB) benefits, you will automatically get Part A and Part B beginning on the first day of the month that you turn 65 (if your birthday is the first of the month, Part A and Part B will begin on the first day of the previous month).
If you are under 65 and have a disability, you will automatically get Part A and Part B after receiving Social Security disability benefits or certain disability benefits from the RRB for 24 months.
If you have ALS (amyotrophic lateral sclerosis, also called Lou Gehrig’s disease), you will automatically receive Part A and Part B the month your Social Security disability benefits start. If you are automatically enrolled, you will receive your red, white, and blue Medicare card in the mail 3 months before your 65th birthday or 25 months of disability benefits. If you do nothing, you will keep Part B and will have to pay.
Part B premiums through your Social Security benefits. You can choose not to keep Part B, but if you decide you want Part B later, you may have to wait to sign up and pay a penalty while you have Part B.