Share: Taking advantage of every opportunity to review your Medicare coverage can help ensure you're receiving the benefits and savings you deserve. The Medicare Advantage Open Enrollment Period was instituted by the Centers for Medicare and Medicaid Services (CMS) in 2019, so it may not be as familiar as other Medicare enrollment periods. Here's what you need to know: When is the Medicare Advantage Open Enrollment Period? The Medicare Advantage Open Enrollment Period occurs from January 1st through March 31st every year. It is different from the Medicare General Enrollment Period, which also occurs from January 1st through March 31st. Note: Medicare General Enrollment is for individuals who did not enroll in Medicare Parts A or B during their Initial Enrollment Period. Enrollments during Medicare General Enrollment go into effect on July 1st of the same year.