Medicare enrollment has specific windows with real consequences if you miss them. Understanding these deadlines is essential — especially the Medigap Open Enrollment Period, which is a use-it-or-lose-it opportunity.
Initial Enrollment Period (IEP)
7-month window around your 65th birthday
- 3 months before your birthday month + your birthday month + 3 months after
- This is when you sign up for Part A and Part B
- If you enroll in the first 3 months, coverage starts on the 1st of your birthday month
- Missing this window can result in permanent late enrollment penalties
Medigap Open Enrollment Period (OEP)
6 months starting when you are 65+ AND enrolled in Part B
- No insurance company can deny you a Medigap policy during this window
- No health questions, no pre-existing condition exclusions
- After this window closes, carriers CAN and WILL use medical underwriting
- This is the single most important enrollment window for Medigap
Special Enrollment Period (SEP)
Triggered by qualifying life events
- Losing employer coverage, moving to a new area, losing Medicaid
- For Part B: 8-month SEP after employer coverage ends (no penalty)
- For Medigap: guaranteed issue rights exist in specific situations but are more limited
- Does NOT apply to voluntary plan changes
Annual Enrollment Period (AEP)
October 15 – December 7 each year
- For changing Medicare Advantage plans or Part D plans
- NOT for Medigap (Medigap can be changed anytime, but underwriting applies)
- Changes take effect January 1 of the following year
- Most commonly used by people switching between Advantage plans
Late Enrollment Penalties
Missing your enrollment windows can result in permanent premium surcharges:
Part B Penalty
10% premium increase for each 12-month period you delayed without qualifying coverage. This surcharge is permanent — you pay it for as long as you have Part B.
Part D Penalty
1% of the national base premium for each month you delayed without creditable drug coverage. Also permanent.
The number one mistake I see: people turning 65 who are still working assume they can sign up for Medigap whenever they want. Wrong. Your 6-month Medigap Open Enrollment Period is a use-it-or-lose-it window. If you wait until you are 68 to retire and then try to get a Medigap plan, you will face medical underwriting. If you have had a heart attack, cancer, or diabetes, you may be denied entirely. Even if you delay Part B because of employer coverage, talk to a licensed agent BEFORE your 65th birthday to understand your timeline.
Knowledge Check
Answer all questions to unlock the next lesson
Q1.When does your Medigap Open Enrollment Period (OEP) begin?
Q2.What happens if you miss your Medigap Open Enrollment Period and try to apply later?
Q3.Maria turns 65 in June and her Part B starts June 1. When does her Medigap OEP end?
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