The primary medicare enrollment period categories are the Initial Enrollment Period (IEP), the Annual Enrollment Period (AEP) (October 15 to December 7), and the Special Enrollment Period (SEP), which is triggered by certain life events. Understanding these windows is essential for enrolling in coverage, such as Part A, Part B, or a Medicare Advantage plan, and avoiding costly late enrollment penalties.
The Primary Medicare Enrollment Periods Explained
Medicare enrollment is commonly simplified into three general timeframes: the Initial Enrollment Period (IEP) for those turning 65 or becoming newly eligible; the Annual Enrollment Period (AEP) in the fall for routine plan changes; and the Special Enrollment Period (SEP) for qualifying life events. However, this categorization is broad, as the actual rules detail numerous, distinct statutory enrollment periods. These periods—which include the General Enrollment Period (GEP), the Medicare Advantage Open Enrollment Period (MA OEP), and a complex array of SEPs for specific situations like moving or losing employer coverage—are each governed by unique eligibility criteria, deadlines, and effective dates.
Initial Enrollment Period (IEP): The First Time You Enroll in Medicare
The Medicare Initial Enrollment Period is the first time an eligible individual can enroll in Medicare Part A and Medicare Part B.
When does the IEP start and end?
This timeline begins three months before the month of your 65th birthday and continues through the three months following your 65th birthday.
What coverage can you enroll in during your IEP?
During this time, you can enroll in Original Medicare (Part A and Part B). After you enroll in Original Medicare, you will be eligible to enroll in alternative or supplemental coverage, such as a Medicare Advantage (Part C) plan, a Prescription Drug (Part D) plan, or a Medicare Supplement (Medigap) plan.
What is the General Enrollment Period (GEP)?
The Medicare General Enrollment Period (GEP) runs annually from January 1 to March 31. Its primary purpose is to give individuals a chance to enroll in Original Medicare if they missed their Initial Enrollment Period and do not qualify for a Special Enrollment Period (SEP). If you enroll during the GEP, your coverage begins the first day of the month after you sign up, and you may be subject to a late enrollment penalty for Part B (and sometimes Part A) that increases the longer you go without coverage.
Annual Enrollment Period (AEP): Making Yearly Coverage Changes
The Medicare Annual Enrollment Period runs from October 15 to December 7 each year. During this Medicare enrollment period, Medicare beneficiaries can review their current Original Medicare or Medicare Advantage coverage and make changes. Any changes you make during the Medicare Annual Enrollment Period will take effect on January 1st of the following year.
When does the Annual Enrollment Period run?
The Medicare Annual Enrollment Period takes place from October 15 to December 7 each year.
What coverage changes can you make during the AEP?
During AEP, you may:
Switch from Original Medicare to a Medicare Advantage Plan (or vice versa)
Switch from your current Medicare Advantage plan to a different Medicare Advantage plan
Join a Part D plan or drop your current Part D plan
What is the MA OEP, and when should I use it?
The Medicare Advantage Open Enrollment Period (MA OEP) runs from January 1 to March 31, but is only for current Medicare Advantage beneficiaries to make a one-time change to their enrollment. During this time, those enrolled in a Medicare Advantage plan may switch to a new Medicare Advantage plan or drop their plan and return to Original Medicare.
Special Enrollment Period (SEP): Eligibility Due to Life Changes
A Medicare Special Enrollment Period takes place when certain events or life changes occur.
When do you qualify for a Special Enrollment Period?
Qualifying events for an SEP include:
Aging into Original Medicare
Losing your coverage
Gaining or losing eligibility for Medicaid, Extra Help, or a Medicare Savings Program
A full list of Special Enrollment Period qualifying events can be found here.
Does moving trigger an SEP?
Yes. You may qualify for an SEP if you move to a new address that offers different plan options or move out of your current plan's service area.
How do I know if I’m eligible for an SEP?
SEPs are complex and depend on the event, its timing, and proof of the change. A licensed insurance agent from SelectQuote can help you understand SEPs and your coverage options if you qualify.
Missing Enrollment Deadlines Can Result in Penalties
Missing Medicare enrollment deadlines can have long-lasting and costly consequences, often resulting in permanent late enrollment penalties that increase your premiums for the rest of your coverage.
The Lifetime Penalty for Missing Part B
The Medicare Part B late enrollment penalty adds a 10% increase to your standard monthly premium for every full 12-month period you were eligible for Part B but didn't sign up and didn't have other qualifying coverage. This cumulative percentage is then added to your premium, and critically, you must pay this higher amount for the entire time you have Part B coverage. For example, delaying enrollment for 36 months results in a permanent 30% increase to your monthly premium.
How the Part D Penalty is Calculated
The Medicare Part D late enrollment penalty is a surcharge added to your monthly premium if you go 63 or more days in a row without having Part D or other "creditable" prescription drug coverage after your initial enrollment period ends. The penalty is calculated by multiplying 1% of the national base beneficiary premium by the number of full, uncovered months you were eligible but not covered. This penalty is generally continuous (permanent); you must pay it for as long as you have Medicare Part D coverage, even if you switch plans.
Navigating Your Medicare Enrollment
As the Medicare enrollment process is often confusing and complex, using a trusted resource can be a significant advantage. SelectQuote’s licensed insurance agents can help you navigate these complicated choices. We can help you understand enrollment periods, assess your specific healthcare needs, and help you find a Medicare Advantage plan that fits both your budget and your health goals. New to Medicare, recently moved, or lost your health insurance? You may be eligible for a free, no-obligation Medicare Advantage plan review with a licensed agent.
Is there a quiz to determine my enrollment eligibility?
Still unsure about when you can enroll? Our Medicare Enrollment Quiz can help you figure out when you should be eligible to enroll or make changes to your elections.
