The initial enrollment period is the first time you’re eligible for Medicare. You can sign up for Part A and/or Part B then. You have a 7-month period to enroll. It centers on your 65th birthday. It includes: The three months before your birthday month Your birthday month The three months after your birthday month If you were born on the first day of the month, Medicare uses the previous month as your birthday month. For example, if your birthday is August 1, your initial enrollment period is from April 1 to October 31. If your birthday is August 11, your initial enrollment period is from May 1 to November 30. During your initial enrollment period, you can enroll in either: Part C (Medicare Advantage), with or without prescription drug coverage, once you have Medicare Part A and Medicare Part B Part D (prescription drug coverage only) once you have Part A or Part B Once you have Original Medicare (Parts A and B), see if Part C or Part D is right for you. . .