Medicare Open Enrollment Ends December 7. Her November 30 Deadline Could Decide Whether She Can Buy Medigap at All

Medicare’s fall open enrollment runs through December 7, giving millions of people time to review their coverage for 2027. But a woman who turned 65 and started Part B in June faces an earlier deadline. She has until November 30 to buy a Medigap policy without medical underwriting. Starting December 1, insurers in most states can ask about her health, charge her more or reject her application altogether.

This deadline belongs to anyone who signed up for Part B at 65 or older within the past six months and hasn’t bought a supplement yet. If you put off Part B because you’re still covered through a job, your window hasn’t opened. It starts the month your Part B does. All dollar figures below are 2026 plan-year amounts from the Centers for Medicare & Medicaid Services (CMS).

Her Six-Month Medigap Window Ends Before Medicare’s Annual Enrollment Period

Federal law gives her a 6 month window that starts the first month she has Part B and is 65 or older. During that time, an insurance company must sell her any Medigap policy it offers. It can’t use medical underwriting to accept or reject her, and it can’t charge her more for health problems she already has. This is a one-time enrollment opportunity under federal law.

For a June start, the window covers June through November. A diagnosis in August or a new heart prescription in October can’t block her application or raise her price as long as she applies by November 30.

Insurers Can Ask About Her Health Starting December 1

Once the window closes, she could face higher premiums, fewer coverage options or outright rejection based on her medical history, unless she qualifies for another guaranteed-issue protection. Federal guaranteed-issue rights still exist, but they only kick in after specific events, such as losing certain other coverage. Simply changing her mind doesn’t count.

Some states provide additional Medigap protections beyond federal law, including opportunities to buy coverage without medical underwriting or switch policies at certain times. These rules vary by state, and some apply only to people who already have Medigap. She should check with her state insurance department before assuming her options disappear after November 30.

Without a supplement, Original Medicare has no out-of-pocket cap. Take one hospital admission followed by a Medicare-covered 100-day stay in a skilled nursing facility. She would owe the $1,736 Part A deductible plus $217 a day for days 21 through 100, assuming both stays fall within the same benefit period. That’s $19,096 in Part A costs alone. Part B adds 20% coinsurance on everything above the $283 deductible, with no ceiling. As an example, $50,000 of outpatient cancer treatment leaves her owing about $10,000. Plan G pays all of these costs except the Part B deductible. These coinsurance exposures sit alongside the IRMAA surcharges and coverage gaps we cataloged in a free guide to Medicare’s hidden bills, which is worth a look before she locks in a plan.

Medicare’s December 7 Deadline Won’t Extend Her Medigap Protection

Medicare’s annual open enrollment runs from October 15 to December 7, with new coverage starting January 1. It ends a week after her Medigap window, which makes it easy to think she still has until December to decide. She doesn’t. The fall season is for switching Medicare Advantage and Part D plans.

Unlike Medicare Advantage, Medigap has no annual enrollment season under federal law. For most people, switching from Medicare Advantage to Original Medicare with a Medigap policy after their initial enrollment window means passing medical underwriting, unless they qualify for special protections.

That’s why her first choice matters. If she buys Medigap now and later switches to Medicare Advantage for the first time, federal trial rights generally give her up to 12 months to return to Medigap. But if she starts with Medicare Advantage and waits several years before seeking a supplement, insurers in most states can consider her medical history. Buying Medigap during her six-month window can preserve options that may be difficult to recapture later.

Three Things to Do Before November 30

1. Choose between Plan G and Plan N. Medigap benefits are standardized, so Plan G provides the same basic coverage regardless of which insurance company sells it. That makes premiums, future rate increases and the insurer’s pricing method important factors to compare. With Plan G, she pays only the $283 Part B deductible. Plan N costs less each month in exchange for copays at the doctor’s office and the emergency room. It also doesn’t cover excess charges from doctors who bill above Medicare’s approved rates.
2. Get quotes from at least three insurance companies and ask how each one sets its prices. Attained-age policies go up as you age. Issue-age and community-rated policies don’t rise with each birthday. Two premiums that look the same today can drift far apart by age 75.
3. Apply this month and pick your start date. A Medigap policy “will begin the first of the month after you apply, unless you ask for a different effective date.” If she applies in November, coverage starts December 1, with her protection still in place. If she lives in one of the guaranteed-issue or birthday-rule states, her state insurance department can confirm what rights she keeps after November.

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