Medicare Supplement Open Enrollment: 2026 Dates & Rules

Key Takeaways

The Medicare Supplement open enrollment period lasts six months and begins the month you turn 65 and enroll in Part B.

During open enrollment, insurers must sell you any Medigap plan they offer without medical underwriting or premium surcharges.

After the six-month window closes, insurers can deny you coverage or charge higher premiums based on your health history.

A limited set of guaranteed issue rights can reopen access to Medigap after the window closes, but they don't apply to everyone.

What Is the Medigap Open Enrollment Period?

The Medigap open enrollment period is a federally protected enrollment window that gives every eligible beneficiary the right to buy a Medicare Supplement policy without health based barriers. This window is separate from the Medicare Annual Enrollment Period and applies only to Medigap, not to Medicare Advantage or Part D drug plans.

Medigap open enrollment gives beneficiaries a guaranteed right to buy coverage regardless of medical history, which is a right that ends when the window closes and does not resume automatically. For a broader overview of how Medicare coverage fits together across Parts A, B, C and D, that context clarifies where Medigap sits in the overall structure.

Who Qualifies for Medicare Supplement Open Enrollment?

The single governing eligibility condition for Medigap open enrollment is enrollment in both Medicare Part A and Medicare Part B. The open enrollment right is automatic and does not require a separate application. The window begins on its own the moment both Part A and Part B enrollment conditions are met at age 65.

Adults turning 65 who enroll in Part B for the first time.
Adults under 65 who receive Medicare due to a qualifying disability, in states that require insurers to offer Medigap to under-65 enrollees. Federal law does not require insurers to sell Medigap to under 65 Medicare beneficiaries, but some states do mandate it.
Adults who delayed Part B because they had employer coverage and are now enrolling in Part B for the first time.
Retirees who are enrolling in both Part A and Part B simultaneously at age 65 without a prior Medicare enrollment.

When Medigap Open Enrollment Starts and How Long It Lasts

The Medigap open enrollment period starts on the first day of the month in which you turn 65 and are enrolled in Medicare Part B, and runs for exactly six months. The window is not tied to a calendar year and is individual to each beneficiary. It moves with your Part B start date, not a fixed annual schedule.

The most common point of confusion is that beneficiaries who delay Part B enrollment because they have employer coverage begin their Medigap open enrollment when Part B starts, not at age 65.

During that six-month window, insurers cannot ask about your health conditions, cannot charge more because of pre-existing conditions and cannot reject your application. Because every insurer must accept you regardless of health history, price becomes the only variable that matters when comparing the best Medicare Supplement plans in your state.

What Medigap Open Enrollment Guarantees

Medigap open enrollment comes with four specific rights that don't resume after the window closes unless a qualifying life event triggers a separate guaranteed issue right: no medical underwriting, coverage for pre-existing conditions from day one, access to any plan letter the insurer sells and the right to choose any insurer in your state on price alone. All four apply for the full six months and lapse when the window ends.

No Medical Underwriting
Medical underwriting is the process by which an insurer reviews your health history to decide whether to sell you a policy and at what price. During Medigap open enrollment, the insurer cannot conduct underwriting, cannot request your medical records and cannot ask about diagnoses or treatments. Outside this window, underwriting can result in a premium surcharge or outright denial of your application.
Coverage for Pre-Existing Conditions
Medigap coverage applies from day one with no waiting period during open enrollment. In the Medigap context, a pre-existing condition is any condition that was diagnosed or treated in the six months before your Medigap coverage begins. Medigap does not follow the Affordable Care Act's pre-existing condition rules, which apply to individual and employer health plans. The open enrollment guarantee is the only federal protection that eliminates any waiting period for Medigap coverage of those conditions.
Access to Any Plan Letter the Insurer Sells
During Medigap open enrollment, you can choose Plan G, Plan N, Plan F if you are eligible or any other plan letter the insurer offers in your state. No plan letter can be withheld from you based on your health. Plan F is only available to beneficiaries who turned 65 before January 1, 2020. Beneficiaries who became eligible after that date can access Plan G, which covers the same gaps as Plan F except the Part B deductible.
Choice of Insurer Based on Price Alone
During Medigap open enrollment, you can compare Medicare Supplement plan costs across every insurer selling Medigap in your state and select the lowest premium, because no insurer can turn you away based on your health. This is the only window where price is the sole variable. Outside open enrollment, the insurer's willingness to accept you at all becomes the first filter and price becomes secondary.

What Happens After the Medicare Supplement Open Enrollment Period

After the six-month Medigap window closes, federal law no longer requires insurers to sell you a Medigap plan and most states do not fill that gap with their own guaranteed access rules. Only a small number of states, including Connecticut, Massachusetts, Maine, New York and Washington, require year-round guaranteed issue. In the remaining states, the insurer decides whether to accept your application and at what price.


Healthy beneficiary who missed the window	The insurer will likely accept the application but may charge a higher premium based on age-rating practices and health history review.	Compare plans across multiple insurers and request quotes. Some insurers offer more favorable rates than others even outside guaranteed issue.
Beneficiary with a chronic condition who missed the window	The insurer may deny the application or exclude coverage for that condition entirely.	Consider Medicare Advantage if Medigap is unaffordable or unavailable due to health history.
Beneficiary in a state with year-round guaranteed issue (CT, MA, ME, NY, WA)	State law guarantees access to Medigap regardless of health status.	Confirm current state rules before assuming this protection applies, as state laws can change.
Beneficiary who qualifies for a special guaranteed issue right (e.g., losing employer coverage, leaving Medicare Advantage)	Federal law restores guaranteed issue protections for a limited window.	Act within the 63-day window from the triggering event. Do not wait.

Source: Centers for Medicare and Medicaid Services (CMS). State-specific guaranteed issue rules vary and are subject to change. Confirm current rules with your State Health Insurance Assistance Program (SHIP) counselor or your state insurance commissioner.

For beneficiaries who already have Medicare Advantage and are considering switching from Medicare Advantage to a Medigap plan, a guaranteed issue right may apply depending on how long you have been enrolled and why you are leaving.

When You Can Get Medigap Outside Open Enrollment

Federal law creates a separate set of guaranteed issue rights triggered by specific life events. These rights restore the protections of Medigap open enrollment for a limited period, typically 63 days from the triggering event. The 63-day clock starts on the date coverage ends or the date you receive written notice that coverage will end, whichever comes first.


Losing employer or union health coverage	Beneficiaries whose group health plan ends or who retire and lose employer-sponsored coverage	63 days from the date coverage ends
Leaving a Medicare Advantage plan during its first year (trial right)	Beneficiaries who joined Medicare Advantage for the first time and want to return to Original Medicare with a Medigap plan	63 days from the date Medicare Advantage coverage ends
Medicare Advantage plan terminated by the insurer	Beneficiaries whose plan is discontinued and who are disenrolled involuntarily	63 days from the plan termination date
Moving out of the Medicare Advantage plan's service area	Beneficiaries who permanently relocate to a ZIP code outside the plan's coverage area	63 days from the date of the move or coverage loss
Losing Medicaid eligibility	Beneficiaries who were dually enrolled in Medicare and Medicaid and lose Medicaid coverage	63 days from the date Medicaid coverage ends
Medicare SELECT plan no longer available in your area	Beneficiaries enrolled in a Medicare SELECT plan whose plan leaves the service area or is discontinued	63 days from the date coverage ends

Source: Centers for Medicare and Medicaid Services (CMS). Guaranteed issue rights are federally defined and apply in all states. State laws may provide additional triggers beyond those listed here.

DOES YOUR STATE OFFER ADDITIONAL MEDIGAP PROTECTIONS?

Several states go beyond federal law to expand Medigap access. California, Oregon, Missouri, Illinois, Nevada, Idaho, Louisiana and other states (this list is not exhaustive, so verify with your state insurance commissioner) have enacted birthday rule laws, which give beneficiaries a short annual window around their birthday to switch Medigap plans without medical underwriting.

Massachusetts, Maine, Connecticut, New York and Washington require year-round guaranteed issue regardless of health. State rules change, so verify current protections with your State Health Insurance Assistance Program (SHIP) counselor before assuming any state-level right applies to your situation.

How to Sign Up for a Medigap Plan During Your Open Enrollment Period

This process applies to anyone within their six-month Medigap open enrollment window. Part B enrollment must be active or have a confirmed start date before you begin. Completing these steps produces a Medigap policy that is active from your Part B start date or the application approval date, depending on when you apply.

Follow these steps to enroll in a Medigap plan during your Open Enrollment Period:

1
Confirm Your Part B Enrollment Start Date
Your Medigap open enrollment period begins on the first day of the month in which you are both 65 and enrolled in Medicare Part B. If you are still waiting for your Part B card, your effective date determines when the window starts. Do not wait for coverage to begin before applying.
2
Choose the Plan Letter That Matches Your Coverage Needs
Plan G covers the widest range of Original Medicare gaps for beneficiaries who became eligible after January 1, 2020. Plan N offers lower premiums with copays for some office and emergency room visits. Plan F eligibility is limited to beneficiaries who turned 65 before January 1, 2020, as it covers the Part B deductible that newer enrollees cannot access through Medigap.
3
Compare Premiums Across Insurers in Your State
Every insurer selling Medigap must offer standardized plan letters, so Plan G from one insurer covers the same gaps as Plan G from another. The only differences are the premium and the insurer's financial stability. Review Medicare Supplement plan costs by insurer and request quotes from at least three insurers before applying.
4
Apply Directly With the Insurer
Applications can be submitted online, by phone or through a licensed Medicare insurance agent. The insurer cannot ask about your health during Medigap open enrollment and cannot decline your application. Keep a copy of your application and note the submission date.
5
Confirm Your Coverage Start Date and First Premium Due
Medigap coverage typically starts the month your Part B begins, provided you apply before that date. If you apply after Part B starts, your Medigap coverage begins on the first day of the month after the insurer approves your application. Set a reminder to pay your first premium before the due date to avoid a lapse.

How Long Do You Have to Apply During Open Enrollment?

The six-month Medigap window runs from the first day of your Part B enrollment month through the last day of the sixth calendar month. If Part B begins March 1, the open enrollment window runs through August 31. Applications submitted before the window closes are covered by open enrollment rules even if the insurer takes additional time to process and issue the policy.

Do You Pay Both Medicare and Medigap Premiums?

Yes. The Medicare Part B premium is separate from the Medigap premium and is paid directly to the federal government. The 2026 standard Part B premium is $202.90 per month. Medigap premiums vary by plan letter, insurer and the pricing method the insurer uses, which is why comparing quotes across multiple insurers during open enrollment is important.

How Medigap Pricing Methods Affect Your Long-Term Cost

Federal law permits all three Medigap pricing methods and state law determines which are available where you live. Community-rated plans tend to cost more at age 65 but are more predictable over time. Attained-age plans are cheaper at enrollment and increase annually as you get older. The pricing method is a long-term cost decision, not a monthly premium comparison.


Community rating	Every enrollee pays the same premium regardless of age.	Long-term cost risk is lowest, and the premium rises only with medical inflation and insurer rate filings, not with the enrollee's age.
Issue-age rating	The premium is locked to the age at enrollment and does not increase solely because the enrollee gets older.	Long-term risk is moderate (inflation pushes rates up but aging does not).
Attained-age rating	The premium increases with age, with the lowest at 65 and the highest at 80 and beyond.	Long-term cost risk is the greatest of the three methods and the premium may become unaffordable on a fixed income.

State law determines which pricing methods are available. Some states require community rating for all Medigap plans. Confirm available methods with your state insurance commissioner or SHIP counselor.

The pricing method an insurer uses is one reason why the top-rated Medicare Supplement insurers do not always have the lowest starting premium. A community-rated plan with a higher monthly cost at 65 can be the more affordable choice at 80, which is why evaluating long-term cost alongside current premium matters during your open enrollment decision.

Medicare Supplement Open Enrollment: Bottom Line

Your Medigap open enrollment window is the only time you are guaranteed access to any Medicare Supplement plan at standard rates, with no health questions asked. Plan G is the strongest choice for most new enrollees, covering nearly all Original Medicare gaps. Factor in the pricing method before you commit an attained-age plan that is cheap at 65 can become costly by 80. Apply within your six-month window. Waiting puts your guaranteed access at risk.

Medicare Supplement Open Enrollment: FAQ

The following questions cover common points of confusion about Medigap enrollment timing, switching rules, state-level differences and plan selection:

Most beneficiaries assume the Medigap open enrollment period is the same as the Medicare Annual Enrollment Period, which runs October 15 to December 7 each year. The Medicare Annual Enrollment Period applies to Medicare Advantage and Part D drug plans, not Medigap. Medigap open enrollment is a one-time personal window tied to your Part B enrollment date, not a recurring calendar event that reopens every fall.

Federal law no longer requires insurers to sell you a Medigap plan once the six-month window closes and most states do not provide year-round guaranteed access. The insurer can ask about your health history, charge higher premiums based on your medical profile or decline your application outright. Exceptions exist for beneficiaries who qualify for a guaranteed issue right through a life event and for residents of states with birthday rules or year-round access laws such as Connecticut, Massachusetts, Maine, New York and Washington.

Switching Medigap plans after open enrollment is possible but not guaranteed. Outside the open enrollment window, you must apply and the insurer can require medical underwriting unless a guaranteed issue right applies to your situation. Beneficiaries in states with birthday rules can switch Medigap plans annually without underwriting and beneficiaries switching from Medicare Advantage to Medigap may qualify for a guaranteed issue right depending on their circumstances.

Medigap open enrollment governs access only to Medicare Supplement plans and has no effect on Medicare Advantage enrollment. Medicare Advantage has its own enrollment periods: the Initial Coverage Election Period when you first become eligible for Medicare, the Annual Enrollment Period from October 15 to December 7 and the Medicare Advantage Open Enrollment Period from January 1 to March 31. Beneficiaries who want to understand how to enroll in a Medicare Advantage plan will find that process governed by separate federal rules entirely.

Plan G coverage details show that Plan G covers the widest range of Original Medicare gaps for beneficiaries who became eligible after January 1, 2020, including all cost-sharing except the Part B deductible. Plan N costs less in monthly premiums but includes copays for some office and emergency room visits and does not cover Part B excess charges. The right choice depends on how frequently you use medical services and whether your doctors charge fees above the Medicare-approved amount.

About Mark Fitzpatrick

Mark Fitzpatrick, a licensed Property and Casualty (P&C) Insurance Producer in Connecticut, is MoneyGeek's resident insurance expert. He has spent nearly a decade analyzing the market, first at LendingTree and now at MoneyGeek, where he produces original research on hundreds of carriers and millions of rates across auto, home, renters, health and life insurance.

He covers economics and insurance at MoneyGeek, and his work has been featured in The Washington Post, The New York Times and NPR, among other outlets.

Like all MoneyGeek analysts, he draws on independent cost and consumer experience data. No insurance company partnership influences his recommendations.

Mark holds a B.A. from Boston College and an M.A. in Economics and International Relations from Johns Hopkins University. He started his career in financial risk management at State Street and is also a five-time “Jeopardy!” champion.

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