Can You Change Medicare Supplement Plans With Pre-Existing Conditions?

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Updated: July 1, 2026

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Key Takeaways
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You can change Medicare Supplement plans with pre-existing conditions during two federally protected enrollment windows.

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Outside protected windows, insurers in most states can deny or surcharge Medigap applications based on pre-existing conditions.

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Federal guaranteed issue rights give you a 63-day window to switch plans after a qualifying event, per CMS.

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Four states require year-round Medigap acceptance, and 12 additional states plus Indiana in 2026 offer annual birthday rule protections.

Can Insurers Deny You a Medigap Plan Because of a Pre-Existing Condition?

Medigap insurers in most states can deny an application based on pre-existing conditions. That right applies only outside the federally protected enrollment windows. 

Outside a protected window, a Medigap insurer may approve the application with no restrictions if the applicant passes medical underwriting, approve it with a premium surcharge based on health rating (where state law permits), approve it with a waiting period of up to six months for coverage of the flagged condition, or deny coverage outright. 

No federal cap limits the size of a premium surcharge outside protected windows in states that permit health-based rating.

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WHAT IS MEDICAL UNDERWRITING IN MEDIGAP?

Medical underwriting is the process an insurer uses to review a Medigap applicant's health history and diagnoses. Prescription drug records are part of that review. The outcome determines whether the application is approved and at what premium. In ACA-compliant individual and small group markets, pre-existing conditions cannot affect enrollment or premiums.

When Can You Change Medigap Plans Without Medical Underwriting?

Federal law creates two windows during which Medigap insurers cannot apply medical underwriting, cannot deny an application based on health status and cannot charge a premium surcharge based on pre-existing conditions.

These windows are the Medigap open enrollment period and guaranteed issue rights. The open enrollment period opens once and never reopens. Qualifying events can trigger guaranteed issue rights multiple times throughout a beneficiary's life.

During Your Medigap Open Enrollment Period

The Medigap open enrollment period is a six-month window that begins on the first day of the month a beneficiary is both age 65 or older and enrolled in Medicare Part B.

Any Medigap insurer selling plans in the applicant's state must accept the application during this window and cannot deny coverage or charge higher premiums based on health history.

It opens once and doesn't repeat after it closes. The clock starts only when both the age and Part B enrollment conditions are met simultaneously.

When You Have Guaranteed Issue Rights

Guaranteed issue rights are federal protections triggered by qualifying events that give beneficiaries a 63-day window to enroll in a Medigap plan without medical underwriting. Under this window, insurers cannot deny coverage or charge higher premiums based on health status or pre-existing conditions.

The 63-day clock starts on the date prior coverage actually ends, not on the date the beneficiary receives notice that coverage will terminate. Termination notices sometimes arrive weeks before the actual end date. Beneficiaries who calculate their window from the notice date may miss the deadline.

What Events Qualify You for Guaranteed Issue Rights?

CMS defines six qualifying events that activate guaranteed issue rights for Medigap enrollment. The 63-day clock begins when coverage under the prior plan ends. Miss that window and the guaranteed issue right for that qualifying event is gone.

Medigap insurers require written proof of the qualifying event. Proof must accompany your application for the insurer to process it under guaranteed issue. Acceptable documentation includes a plan termination letter or an employer benefit end-date confirmation.

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    Medicare Advantage Plan Termination

    Your Medicare Advantage plan stops participating in Medicare or ends coverage in your service area. CMS designates this event as a guaranteed issue trigger. You have 63 days from the plan's termination date to apply for a Medigap plan without health review.

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    Loss of Employer or Union Group Coverage

    You lose employer-sponsored or union-sponsored supplemental health coverage that supplements your Medicare benefits. The 63-day window starts from the date your group coverage ends, not from the date you receive the termination notice from your employer.

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    Moving Outside Your Plan's Service Area

    You move permanently outside the service area of your Medicare Advantage or Medicare SELECT plan. You must disenroll from the existing plan before the guaranteed issue window begins.

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    Returning to Original Medicare Within Your First Year of Medicare Advantage

    You enrolled in a Medicare Advantage plan for the first time at age 65 and decide within the first 12 months to return to Original Medicare. CMS extends a trial right that functions as a guaranteed issue trigger for one Medigap plan.

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    Leaving Medicare Advantage After Switching From a Medigap Plan

    You dropped your Medigap plan to join a Medicare Advantage plan and left within the first 12 months. CMS restores a guaranteed issue right so you can re-enroll in the same Medigap plan you previously held or in a comparable one with equal or lesser benefits.

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    Your Medigap Insurer Goes Bankrupt or Exits Medicare

    Your Medigap insurer is declared insolvent or loses its Medicare certification. CMS treats this event as a guaranteed issue trigger and your 63-day window begins on the date the insurer's coverage ends, not the date bankruptcy proceedings begin.

Which States Allow Medigap Plan Changes With Pre-Existing Conditions?

Some states have enacted rules beyond federal guaranteed issue. Beneficiaries in these states can switch Medigap plans more freely regardless of health status. 

Two categories of state-level rule exist. Year-round open enrollment is available in four states: insurers must accept all Medicare beneficiaries at any time without medical underwriting. 

The birthday rule is active in 12 states plus Indiana as of 2026. Beneficiaries have an annual window around their birthday to switch to a plan with equal or fewer benefits without medical underwriting.

These protections apply to beneficiaries who qualify for Medicare and reside in the applicable state at the time of application.

State
Protection Type
Annual Window
Underwriting Waived

California

Birthday rule

30 days after birthday

Yes, for plans with same or fewer benefits

Connecticut

Year-round open enrollment

Any time

Yes

Idaho

Birthday rule

63 days after birthday

Yes, for plans with same or fewer benefits

Illinois

Birthday rule

45 days after birthday

Yes, for plans with same or fewer benefits

Indiana

Birthday rule (effective 2026)

30 days after birthday

Yes, for plans with same or fewer benefits

Idaho offers 63 days, Kentucky and Nevada offer 60 days. California's 30-day window requires action as soon as your birthday month begins.   

The birthday rule doesn't give beneficiaries the right to upgrade to a plan with more benefits. In birthday rule states, the new plan must have equal or fewer benefits than the current one. A beneficiary who wants more benefits is subject to full medical underwriting outside these windows.  

Plan G and Plan N are the most common choices since Plan F closed to new enrollees in 2020. Premiums for the same plan letter differ by insurer and state.

How Do You Change Medigap Plans With a Pre-Existing Condition?

Beneficiaries with a confirmed federal guaranteed issue right, or those in a state with birthday rule or year-round open enrollment protections, can use this process. Before starting, confirm the qualifying triggering event and check that the enrollment window is still open.

  1. 1
    Confirm Your Guaranteed Issue Right or State Eligibility

    Identify whether a federal triggering event applies to your situation, such as losing employer coverage, your Medicare Advantage plan terminating or permanently moving outside your plan's service area, or whether you live in a state with a birthday rule or year-round open enrollment. 

    A plan termination letter or employer benefit end-date notice serves as proof when the qualifying event is employer coverage loss or Medicare Advantage termination. Birthday rule applications require a birth certificate. The new Medigap insurer will request this proof. Submit it with your application.

    Without a confirmed qualifying event, birthday rule window or year-round open enrollment eligibility, the insurer applies full medical underwriting. Full medical underwriting can result in a denial or a premium surcharge based on your health history.

  2. 2
    Compare Plan Letters Available in Your State

    Review the Medicare Supplement plan letters available in your state, focusing on Plan G and Plan N, which are the two most enrolled plans since Plan F closed to applicants new to Medicare in 2020, per CMS. 

    Benefits for the same plan letter are standardized by CMS regardless of insurer, so the only variables across companies for the same letter are the monthly premium and the pricing structure (attained-age, issue-age or community-rated).

  3. 3
    Apply Directly With the New Insurer During Your Window

    Contact the insurer of the plan you want and complete the application, stating that you are applying under guaranteed issue rights and identifying the specific triggering event by name. 

    Submit your application as early in the 63-day window as possible. Early submission allows processing time and reduces the risk of a gap between your old plan ending and your new plan starting.

  4. 4
    Confirm the Effective Date Before Canceling Your Old Plan

    Once the new insurer confirms your coverage effective date in writing, notify your current Medigap insurer in writing that you are canceling your policy, using the cancellation procedure required in your state.

    Canceling your existing plan before receiving written confirmation of the new plan's start date creates a coverage gap. A gap leaves you responsible for Medicare's 20% coinsurance on Part B services with no annual cap.

    Set the cancellation date for your old plan to match the new plan's effective date exactly so there's no gap and no period where you're paying premiums on two Medigap plans simultaneously.

  5. 5
    Notify Your Health Care Providers of the Coverage Change

    Before your first medical appointment under the new Medigap plan, inform your primary care physician and any active specialists of the insurer change so their billing staff can route secondary claims to the correct Medigap company.  

    Your providers bill Original Medicare first. Medicare pays its portion directly, then forwards the secondary claim to the Medigap insurer. A billing address error at this step can delay reimbursement by weeks.

What Are Your Options if You're Denied a Medigap Plan?

A Medigap denial under medical underwriting doesn't close off all coverage options. After a denial, you can apply to a different Medigap insurer, switch to Medicare Advantage or contact a State Health Insurance Assistance Program (SHIP) counselor to find state-specific options.

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    Apply to Additional Medigap Insurers

    Each Medigap insurer maintains its own underwriting criteria. A denial from one company is not binding on others. Applying to multiple insurers gives you more chances to find a plan, though premiums and underwriting decisions will vary by company.

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    Enroll in Medicare Advantage During Annual or Special Enrollment

    Medicare Advantage plans cannot deny enrollment based on pre-existing conditions during the annual enrollment period (October 15 to December 7) or during applicable special enrollment periods, per CMS.

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    Contact Your State SHIP Office for Free Guidance

    State Health Insurance Assistance Program (SHIP) counselors provide free, unbiased guidance on Medigap eligibility, state-specific protections and coverage options for beneficiaries with pre-existing conditions. SHIP offices are federally funded and available in all 50 states.

    Don't apply directly if you're unsure whether your triggering event qualifies. A rejected guaranteed issue application doesn't reset your 63-day clock. Contact your state SHIP office first to confirm your eligibility, SHIP counselors can verify your qualifying event before you apply, at no cost.

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    Check for State High-Risk Pool or Additional State Protections

    A small number of states maintain high-risk pools or extended guaranteed issue protections for Medigap applicants who have been denied under medical underwriting. Contact your state insurance commissioner's office to confirm which protections, if any, apply in your state.

Bottom Line

In most states, insurers can deny a Medigap application based on pre-existing conditions once a guaranteed issue period or state birthday window has passed. Apply as soon as possible if you're within 63 days of losing prior coverage or your state's annual birthday window is approaching. 

Miss that deadline and full medical underwriting starts. At that point, the insurer can deny your application or add a premium surcharge. 

My recommendation for most readers who've missed their open enrollment: contact your state SHIP office before applying anywhere. A SHIP counselor can confirm whether a birthday rule window is coming up, which is often the only path left without medical underwriting. It's free, takes one call and can prevent a denial from closing your options.

Medicare Supplement Plan Changes With Pre-Existing Conditions: FAQ

Know more about changing Medicare Supplement plans with pre-existing conditions, like cover guaranteed issue rights, state birthday rules and how medical underwriting applies:

About Mark Fitzpatrick

Mark Fitzpatrick, Licensed P&C Insurance Expert, MoneyGeek

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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