Open Enrollment Lets You Change Advantage Plans With No Questions Asked. It Does Not Promise You Medigap. That Application Still Asks About Your Health.
Switching Medicare Advantage plans during Open Enrollment is simple, but the move back to Original Medicare with a Medigap supplement can collapse entirely depending on what your health history says about you now versus when you were 65.
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A 71-year-old on a Medicare Advantage plan gets a letter in September saying her cardiologist will not be in the network next year. She circles October 15 on the calendar, planning to leave the plan during Medicare Open Enrollment and return to Original Medicare with a Medigap policy. Leaving Advantage is the easy part. The Medigap application is where the plan can come apart.
The collision is most consequential for someone who has passed the one-time Medigap enrollment window and developed health problems since turning 65. Medicare Open Enrollment changes the right to enter or leave an Advantage plan. It does not change a Medigap insurer’s right to use medical underwriting.
What Open Enrollment Actually Covers
Medicare Open Enrollment runs from October 15 through December 7. During that period, a beneficiary can join, switch or drop a Medicare Advantage plan. Someone returning to Original Medicare can also enroll in a standalone Part D prescription drug plan. Medigap is not part of that annual enrollment menu. A person may apply for a policy, but Open Enrollment does not require the carrier to approve it or prevent the insurer from asking about the applicant’s health.
That creates two decisions with different rules. Returning to Original Medicare is an enrollment choice. Adding Medigap is an insurance application that can still be declined.
Without a supplement, Original Medicare has no annual out-of-pocket maximum. A hospital admission carries a $1,736 Part A deductible per benefit period in 2026. Hospital days 61 through 90 cost $434 each, while a qualifying skilled-nursing stay costs $217 a day from days 21 through 100. Part B adds a $283 annual deductible followed by 20% of the Medicare-approved amount for most services, with no annual ceiling. Returning to Original Medicare before securing Medigap can therefore leave far more exposure than the member intended (we cataloged the surcharges, deductibles, and coverage gaps that ambush retirees in a free Medicare guide here).
Why the Application Still Asks About Health
The one-time federal Medigap Open Enrollment Period begins the first month a person is at least 65 and enrolled in Part B. It lasts six months and does not return every fall. During those six months, a carrier cannot deny coverage or charge more because of the applicant’s health. Once the window closes, insurers in most states can ask about diabetes, heart disease, cancer, oxygen use, joint replacements and current medications. They can charge more or decline the application.
Federal guaranteed-issue rights reopen the door in certain circumstances, including some plan terminations, losses of employer or union coverage and trial rights for people who recently entered Medicare Advantage for the first time. A cardiologist leaving the network does not ordinarily create that protection by itself. That is the switch-back trap. A $0-premium Advantage plan may feel reversible at 65. At 71, a stent, diabetes diagnosis or expensive prescription can stand between the member and Plan G.
State Protections Do Not All Work the Same Way
Federal law sets the floor, but state law can widen the path back to Medigap. New York, Connecticut and Massachusetts provide unusually broad access to Medigap without medical underwriting. Other states offer narrower enrollment protections that apply only at certain times or to certain applicants. California and Oregon, for example, have birthday rules that let many people who already own Medigap switch to a policy with equal or lesser benefits without new underwriting. Those rules generally do not give an Advantage member an unrestricted first chance to buy Medigap.
That is why “my state has a birthday rule” is not enough. The question is whether the rule protects someone in this applicant’s exact position.
The Order of Operations Matters
Between October 15 and December 7, three steps keep the coverage decision from getting ahead of the underwriting decision:
- Apply for Medigap first. Obtain written approval and coordinate the effective date before completing the move out of Advantage.
- If the Medigap application is declined, compare the other Advantage plans available for January. Check the cardiologist, prescriptions and preferred hospital against the new network and formulary.
- Confirm state protections with the insurance department or State Health Insurance Assistance Program. A state window may protect existing Medigap policyholders without helping someone coming from Advantage.
Open Enrollment makes the Advantage exit easy. It does not make the landing automatic. Secure the supplement first, and January remains a coverage choice instead of a leap.
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Gerelyn Terzo is the author of dividend investing handbook "Dividend Investing Strategies: How to Have Your Cake & Eat It Too." A veteran financial journalist, she covers agri-finance for outlets like Global AgInvesting and the broader stock market and personal finance for 24/7 Wall Street. She began at CNBC and later helped launch Fox Business in New York. Gerelyn currently resides in Woodland Park, Colorado and dabbles in nature photography as a hobby.
