3 months before Initial Enrollment Period 2 months before 1 month before 65th Birthday month 1 month after 2 months after 3 months after Initial Enrollment Period (IEP) If you are enrolling in Medicare for the first time, your IEP begins 3 months before and ends 3months after you turn 65 You may enroll in Part A, Part B, or both. Additionally, you can choose to enroll in Medicare Advantage, Medicare Supplement, or Prescription Drug plan You are not required to enroll in Part D. However, for each full month you did not have creditable drug coverage, there is a penalty of 1% of the national base beneficiary premium