Guide to Medicare Enrollment Periods
Understanding when you can enroll in Medicare is just as important as understanding what Medicare covers. Missing an enrollment deadline can result in gaps in coverage and permanent late enrollment penalties that increase your monthly premiums for as long as you have Medicare.
Enrollment Periods at a Glance
| Enrollment Period | Abbrev. | When | Who It's For |
|---|---|---|---|
| Initial Enrollment Period | IEP | 7-month window around 65th birthday | People newly eligible |
| Annual Enrollment Period | AEP | October 15 – December 7 | All Medicare beneficiaries |
| General Enrollment Period | GEP | January 1 – March 31 | People who missed their IEP |
| MA Open Enrollment | OEP | January 1 – March 31 | Current MA plan members |
| Special Enrollment Period | SEP | Varies by qualifying event | People with qualifying life events |
Initial Enrollment Period (IEP)
Your first chance to enroll in Medicare
When It Happens
A 7-month window that includes the 3 months before your 65th birthday, your birthday month, and the 3 months after. If you qualify due to disability, your IEP begins 3 months before your 25th month of receiving Social Security disability benefits.
Coverage Start Dates
- •Enroll during the 3 months before your birthday — coverage starts the 1st of your birthday month
- •Enroll during your birthday month — coverage starts the 1st of the following month
- •Enroll 1–3 months after — coverage is delayed by 1–3 months
Tip: Enroll during the first 3 months of your IEP to ensure seamless coverage starting on your 65th birthday.
Annual Enrollment Period (AEP)
Your yearly opportunity to make changes
When It Happens
October 15 through December 7 each year. Changes made during this period take effect January 1 of the following year.
What You Can Do
- checkSwitch from Original Medicare to a Medicare Advantage plan
- checkSwitch from Medicare Advantage back to Original Medicare
- checkChange to a different Medicare Advantage plan
- checkJoin, switch, or drop a Part D prescription drug plan
Tip: Review your plan's Annual Notice of Change (ANOC) each fall. Plans can change their premiums, benefits, and drug formularies from year to year.
Special Enrollment Period (SEP)
For qualifying life events
What Triggers a SEP
Certain life events allow you to make changes outside regular enrollment periods:
- •Moving to a new area with different plan options
- •Losing employer or union health coverage
- •Gaining or losing Medicaid eligibility
- •Moving into or out of a nursing home or long-term care facility
- •Your plan leaves Medicare or stops providing care in your area
Tip: SEPs have time limits. Act quickly once you experience a qualifying event — many SEPs last only 2–3 months.
General Enrollment Period (GEP)
A second chance if you missed your IEP
When It Happens
January 1 through March 31 each year. Coverage begins July 1 of that year.
The GEP is designed for people who missed their Initial Enrollment Period and didn't qualify for a Special Enrollment Period. While it provides a path to coverage, enrolling during the GEP typically results in late enrollment penalties.
Note: Enrolling during the GEP may mean paying higher premiums due to late enrollment penalties, and you'll have a gap in coverage until July 1.
Medicare Advantage Open Enrollment Period (OEP)
For current Medicare Advantage members only
When It Happens
January 1 through March 31 each year. Changes take effect the first of the month after you enroll.
What You Can Do
- checkSwitch to a different Medicare Advantage plan
- checkReturn to Original Medicare (and join a standalone Part D plan)
Tip: You can only make one plan change during the OEP. If you enrolled in a MA plan during the AEP and it's not the right fit, the OEP gives you one chance to switch.
Late Enrollment Penalties
Missing enrollment deadlines can cost you
Part B Late Enrollment Penalty
If you don't sign up for Part B when first eligible, you may pay a late enrollment penalty of 10% for each 12-month period you could have had Part B but didn't. This penalty is added to your monthly premium for as long as you have Part B.
Part D Late Enrollment Penalty
If you go 63 days or more without creditable prescription drug coverage, you may pay a penalty of 1% of the national base beneficiary premium for each month you didn't have coverage. This penalty is added to your monthly premium for as long as you have Part D.
How to Avoid Penalties
- checkEnroll during your Initial Enrollment Period
- checkMaintain creditable coverage through an employer or union plan
- checkQualify for a Special Enrollment Period when you lose other coverage
Need Help Understanding Your Options?
Our licensed agents are here to guide you through the process — at no cost to you.