Medicare Open Enrollment Ends December 7, But Her November 30 Medigap Deadline Arrives First

She turned 65 in June, signed up for Medicare Part B, and assumed the December 7 open enrollment date covered every choice she had. It does not, and the window closes before many people even realize a separate one exists.

This post may contain links from our sponsors and affiliates, and Flywheel Publishing may receive compensation for actions taken through them.

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 enrolled in Part B in June faces an earlier cutoff. She has until November 30 to buy a Medigap policy without medical underwriting. After that, insurers in most states can ask about her health, charge a higher premium, or deny the application altogether.

This deadline applies to anyone who enrolled in Part B at age 65 or older within the past six months and has not yet bought a supplement. If you delayed Part B because you are still covered through work, your window has not started yet. It begins the month your Part B coverage begins. 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 six-month window that starts the first month she has Part B and is 65 or older. During that period, an insurance company must sell her any Medigap policy it offers. It cannot use medical underwriting to approve or deny her, and it cannot charge more because of preexisting health conditions. This is a one-time enrollment chance under federal law.

For a June start, the window runs from June through November. A diagnosis in August or a new heart medication in October cannot block her application or increase her price as long as she applies by November 30.

Insurers Can Start Reviewing Her Health After November 30

Once the window closes, she could face higher premiums, fewer plan choices, or a rejection based on her medical history unless she qualifies for another guaranteed-issue right. Federal guaranteed-issue protections still exist, but they apply only after certain events, such as losing some other coverage. Simply changing her mind does not qualify.

Some states add their own Medigap protections beyond federal law, including chances to buy coverage without medical underwriting or switch policies during certain periods. These rules differ 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 maximum. Consider 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 totals $19,096 in Part A costs alone. Part B adds 20% coinsurance on amounts above the $283 deductible, with no cap. For example, $50,000 in outpatient cancer treatment would leave her responsible for about $10,000. Plan G covers all of those costs except the Part B deductible. Those coinsurance exposures, along with IRMAA surcharges and other coverage gaps, are laid out in a free guide to Medicare’s hidden bills, which is worth reviewing before she commits to a plan.

Medicare’s December 7 Deadline Does Not Extend Medigap Coverage

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 does not. The fall season is for switching Medicare Advantage and Part D plans.

Unlike Medicare Advantage, Medigap does not have an annual enrollment season under federal law. For most people, moving from Medicare Advantage to Original Medicare with a Medigap policy after the initial enrollment period means going through medical underwriting unless they qualify for special protections.

That is why the first choice matters so much. 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 review her medical history. Buying Medigap during the six-month window can preserve options that may be hard to get back 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 no matter which insurer sells it. That makes premiums, future rate increases, and the company’s pricing method the key things to compare. Under Plan G, she pays only the $283 Part B deductible. Plan N usually costs less each month in exchange for copays at the doctor’s office and the emergency room. It also does not cover excess charges from doctors who bill above Medicare’s approved rates.
2. Get quotes from at least three insurers and ask how each one sets prices. Attained-age policies rise as you get older. Issue-age and community-rated policies do not increase with every birthday. Two premiums that look similar now can diverge sharply by age 75.
3. Apply this month and choose your effective date. A Medigap policy will generally begin on the first day of the month after you apply unless you request a different start date. If she applies in November, coverage starts December 1, keeping her protected. If she lives in a guaranteed-issue or birthday-rule state, her state insurance department can confirm what rights remain after November.