2026 Medicare Enrollment Periods at a Glance
| Period | Dates | What You Can Do |
|---|---|---|
| Initial Enrollment Period (IEP) | 7-month window around your 65th birthday | Sign up for Part A, Part B, Part D, or Medicare Advantage for the first time |
| Annual Enrollment Period (AEP) | October 15 – December 7, 2026 | Switch MA plans, join/drop Part D, switch from MA to Original Medicare (or vice versa) |
| Medicare Advantage OEP | January 1 – March 31, 2026 | Switch MA plans or drop MA and return to Original Medicare + standalone Part D |
| General Enrollment Period (GEP) | January 1 – March 31, 2026 | Sign up for Part A and/or Part B if you missed your IEP (coverage starts July 1) |
| Part D IEP | Same as Medicare IEP | Join a Part D plan when first eligible for Medicare |
| Medigap Open Enrollment | 6 months starting when you turn 65 and have Part B | Buy any Medigap plan with guaranteed issue (no health questions) |
| Special Enrollment Period (SEP) | Varies by qualifying event | Enroll or make changes due to moves, loss of coverage, or other life events |
Initial Enrollment Period (IEP)
Your IEP is a 7-month window centered on your 65th birthday month. It begins 3 months before you turn 65 and ends 3 months after. This is the most important enrollment window — missing it can result in late enrollment penalties.
Annual Enrollment Period (AEP)
The AEP runs from October 15 through December 7 every year. During this period, you can:
- Switch from Original Medicare to a Medicare Advantage plan
- Switch from one MA plan to another
- Drop your MA plan and return to Original Medicare
- Join, switch, or drop a Part D prescription drug plan
Changes made during AEP take effect January 1 of the following year.
Medicare Advantage Open Enrollment Period (OEP)
If you’re already enrolled in a Medicare Advantage plan, you can use the OEP (January 1 – March 31) to:
- Switch to a different Medicare Advantage plan
- Drop your MA plan and return to Original Medicare (and join a standalone Part D plan)
Special Enrollment Periods (SEPs)
You may qualify for a Special Enrollment Period if you experience certain life events:
- You move to a new area with different plan options
- You lose employer or union health coverage
- You qualify for Extra Help/Low-Income Subsidy
- You’re newly eligible for Medi-Cal
- You leave a PACE program
- You’re affected by a natural disaster (relevant for wildfire-prone California)
Don’t Miss Your Window
Missing enrollment periods can mean going without coverage or paying permanent penalties. A licensed Medicare agent can help you understand your options and deadlines.
When is Medicare Open Enrollment 2026?
The Annual Enrollment Period (AEP), commonly called Open Enrollment, runs from October 15 to December 7, 2026. Changes made during this period take effect January 1, 2027.
What happens if I miss my Initial Enrollment Period?
If you miss your IEP and don't have qualifying coverage, you'll need to wait for the General Enrollment Period (Jan 1 – Mar 31) and may face permanent late enrollment penalties for Part B (10% per year delayed) and Part D (1% per month delayed).
Can I switch Medicare plans outside of Open Enrollment?
You can only switch plans outside of AEP if you qualify for a Special Enrollment Period due to certain life events like moving, losing employer coverage, or qualifying for Medi-Cal.
When can I sign up for Medigap in California?
Your Medigap Open Enrollment Period starts the month you turn 65 and are enrolled in Part B. This 6-month window gives you guaranteed issue rights. California also offers a birthday rule allowing annual plan switches.