Enrollment Periods
Every Medicare enrollment window you need to know — missing the wrong one can cost you for life.
Why Enrollment Periods Matter
Medicare enrollment isn't as simple as signing up whenever you want. There are specific windows when you can enroll, make changes, or switch plans — and missing the wrong window can mean gaps in coverage, permanent penalties, or being stuck with a plan you don't want for a full year.
Initial Enrollment Period (IEP)
This is your first opportunity to enroll in Medicare. It's a 7-month window:
- 3 months before your 65th birthday month
- Your birthday month
- 3 months after your birthday month
Enroll in the 3 months before your birthday month and coverage starts the first of your birthday month. Enroll during your birthday month or the 3 months after, and coverage starts the first of the month after you sign up.
💡 If you're still working at 65 and have employer coverage through a current employer with 20 or more employees, you may be able to delay both Part A and Part B without penalty. Ask your HR department and confirm in writing.
⚠️ HSA Users — Important: If you are still working at 65 and contributing to a Health Savings Account (HSA), you should delay both Part A and Part B. The moment you enroll in any part of Medicare — including premium-free Part A — you are no longer allowed to contribute to an HSA. Most people know to delay Part B with employer coverage, but don't realize that enrolling in Part A also stops HSA contributions. If you want to continue contributing to your HSA, delay both parts until you stop working. You will not be penalized for this as long as you have creditable employer coverage.
💡 Confused about YOUR dates? This is the module where mistakes get expensive. One call with your birthday and work situation, and Matt will lay out every window that applies to you — in writing.
Special Enrollment Period (SEP)
If you delayed Medicare because you had coverage through a current employer (yours or a spouse's), you qualify for a Special Enrollment Period when that coverage ends. You have 8 months to enroll in Part A and/or Part B without penalty.
Important: COBRA and retiree health coverage do NOT count as current employer coverage for SEP purposes.
Robert H. retired at 66 and stayed on COBRA because it felt like "keeping his coverage." Nobody told him COBRA doesn't count as employer coverage for Medicare's Special Enrollment Period. By the time COBRA ran out, his 8-month window had closed — he had to wait for the General Enrollment Period, went months without Part B, and now pays a late enrollment penalty on top of his premium. Every month. For life. One 10-minute conversation before he retired would have prevented all of it.
Client stories reflect real situations from Matt's practice. Names and identifying details are changed for privacy.
General Enrollment Period (GEP)
If you missed your IEP and don't qualify for an SEP, you can enroll during the General Enrollment Period: January 1 – March 31 each year. Your coverage starts the first of the month after you sign up. Late enrollment penalties will apply.
Annual Election Period (AEP) — Open Enrollment
Every year from October 15 – December 7, anyone with Medicare can:
- Switch from Original Medicare to Medicare Advantage (or vice versa)
- Switch from one Medicare Advantage plan to another
- Join, switch, or drop a Part D drug plan
Changes made during AEP take effect January 1 of the following year.
Medicare Advantage Open Enrollment Period (OEP)
From January 1 – March 31 each year, if you're enrolled in a Medicare Advantage plan you can:
- Switch to a different Medicare Advantage plan
- Switch back to Original Medicare (and enroll in a standalone Part D plan)
Medigap Open Enrollment Period
This is the most important window for Medigap: a 6-month period starting when you're 65 and enrolled in Part B. During this window you have a guaranteed right to buy any Medigap plan sold in your state — insurers cannot deny you or charge more based on health conditions.
⚠️ After your Medigap Open Enrollment Period ends, insurers can use medical underwriting. If you develop a health condition, you may be denied or charged significantly more. This window only comes once — use it wisely.
Special Enrollment Periods for Medicare Advantage & Part D
Certain life events — moving out of your plan's service area, losing employer coverage, qualifying for Medicaid, or your plan leaving Medicare — trigger Special Enrollment Periods that allow you to make changes outside the normal windows.
Prefer to watch?
Matt covers everything in this module on video:
Get Your Exact Dates
Tell Matt your birthday and whether you're still working — he'll map every enrollment window that applies to you, so you never face a penalty that lasts the rest of your life.
📞 Call or Text Matt: (248) 895-6656 Have Matt Call You Instead →