You are enrolled in Part A automatically at age 65, or when you qualify through disability- there is no additional premium for Part A.
You must elect Medicare Part B if
- You are not getting Social Security or Railroad Retirement Board benefits (for example, you are still working).
- You qualify for Medicare because you have End-Stage Renal Disease(ESRD).
- Apply 3 months before age 65, and 3 months after (7 months in total including the birthday month).
- Medicare coverage becomes effective on the 1st day of the month of your birthday unless your birthday is on the 1st (assuming you apply in a timely manner).
- There is a monthly premium for Part B coverage.