The main Medicare enrollment windows
| Window | Dates | Who it's for |
|---|---|---|
| Initial Enrollment Period (IEP) | 7 months around your 65th birthday | Newly eligible — first time enrolling |
| Annual Enrollment Period (AEP) | October 15 – December 7 | Everyone with Medicare can change plans |
| Medicare Advantage OEP (MA-OEP) | January 1 – March 31 | Current MA members switching once or returning to Original |
| General Enrollment Period (GEP) | January 1 – March 31 | Late enrollers without creditable coverage (penalty usually applies) |
| Medigap Open Enrollment | 6 months from Part B start | One-time, guaranteed-issue Medigap window |
| Special Enrollment Period (SEP) | Varies by trigger | Move, loss of coverage, plan non-renewal, etc. |
What you can do during each window
AEP (October 15 – December 7) is the big one. During AEP, any Medicare beneficiary in Ohio can:
- Switch from Original Medicare to Medicare Advantage
- Switch from Medicare Advantage to Original Medicare
- Switch between Medicare Advantage plans
- Enroll in, switch, or drop a standalone Part D plan
Changes take effect January 1 of the following year. There's no other annual window with this much flexibility.
MA-OEP (January 1 – March 31) is more restrictive. You can use it to switch MA plans once, or drop MA and go back to Original Medicare with a standalone Part D plan. You cannot use MA-OEP to switch into MA from Original Medicare.
Special Enrollment Periods are triggered by qualifying life events — moving, losing employer coverage, plan non-renewal, qualifying for Medicaid or Extra Help, and others. SEPs let you make changes outside AEP without waiting.
The Ohio-specific Medigap window matters most at 65
Ohio is a fully-underwritten Medigap state most of the time — meaning insurers can decline applicants or charge more based on health history. The exception is your 6-month Medigap Open Enrollment Period, which starts the month you turn 65 and are enrolled in Part B. During this window, all Ohio Medigap insurers must sell you any policy they offer at the best rate, regardless of health. After it closes, Ohio insurers can decline you or charge a higher premium.
This is why the 6-month Medigap window matters so much in Ohio — it's the one time when you have unrestricted Medigap shopping power. After it closes, switching from Medicare Advantage back to Medigap usually requires passing underwriting.