Most people should enroll in Medicare during their Initial Enrollment Period (IEP), which begins three months before the month they turn 65, includes their birthday month, and continues for three months after. Enrolling during this window helps avoid late enrollment penalties and gaps in coverage.
If you are still working and covered by employer-sponsored health insurance, you may be able to delay Medicare Part B and Part D without penalty, depending on whether your coverage is considered creditable. After leaving employer coverage, you typically qualify for a Special Enrollment Period to enroll in Medicare.
Because enrollment timing affects premiums and penalties, reviewing your situation before turning 65 is important.