The program offers a range of benefits to help individuals manage their health care expenses, including hospital insurance (Part A), medical insurance (Part B), prescription drug coverage (Part D), and Medicare Advantage (Part C). However, to access these benefits, individuals must enroll in Medicare during specific enrollment periods.

There are various enrollment periods for Medicare, each with its own set of rules and eligibility criteria. Here is a breakdown of the different enrollment periods and what you need to know about each:

Initial Enrollment Period (IEP)
The Initial Enrollment Period is the first opportunity for eligible individuals to enroll in Medicare. The IEP lasts for seven months and begins three months before the month of an individual’s 65th birthday and ends three months after their 65th birthday. If an individual is already receiving Social Security benefits, they will be automatically enrolled in Medicare Parts A and B during their IEP.

General Enrollment Period (GEP)
The General Enrollment Period is for individuals who missed their IEP and did not sign up for Medicare during a Special Enrollment Period (SEP). The GEP runs from January 1st to March 31st every year, and coverage begins on July 1st. However, individuals who enroll during the GEP may be subject to late enrollment penalties.

Special Enrollment Period (SEP) 
The Special Enrollment Period is for individuals who experience certain qualifying life events, such as moving to a new area or losing employer-sponsored health insurance. The SEP allows these individuals to enroll in Medicare outside of the standard enrollment periods. The length of the SEP and the eligibility criteria vary depending on the qualifying life event.

Annual Enrollment Period (AEP)
The Annual Enrollment Period, also known as the Open Enrollment Period, is an opportunity for individuals to make changes to their Medicare coverage. The AEP runs from October 15th to December 7th every year, and changes made during this period take effect on January 1st of the following year. During the AEP, individuals can switch from Original Medicare to Medicare Advantage or make changes to their Medicare Advantage or Part D plan.

Medicare Advantage Open Enrollment Period (OEP)
The Medicare Advantage Open Enrollment Period allows individuals who are already enrolled in a Medicare Advantage plan to switch to a different Medicare Advantage plan or return to Original Medicare. The OEP runs from January 1st to March 31st every year.

Medicare Supplement Enrollment Period
​Medicare Supplement plans, also known as Medigap plans, help individuals cover the out-of-pocket costs associated with Original Medicare. The Medicare Supplement Enrollment Period is a six-month window that begins on the first day of the month in which an individual turns 65 and is enrolled in Medicare Part B. During this period, individuals can enroll in a Medicare Supplement plan without undergoing medical underwriting.