Medigap

Original Medicare has broad provider access, but it leaves deductibles and coinsurance and has no annual out-of-pocket limit for Part A and Part B services. Medigap policies are sold by private insurers to cover defined portions of those remaining costs.

• Medigap only works with Original Medicare—not Medicare Advantage.
• It generally pays after Original Medicare processes a covered claim.
• It does not generally cover long-term care, routine dental or vision care, or private-duty nursing.
• A separate Part D plan may be needed for outpatient prescriptions.

Start with the broader Medicare guide if the difference between Original Medicare and Medicare Advantage is not yet clear.

In most states, Medigap policies are standardized into lettered plans. A Plan G from one carrier has the same basic standardized benefits as a Plan G from another carrier, but the premium, rating method, customer service, and available discounts can differ. Massachusetts, Minnesota, and Wisconsin standardize policies differently.

The federal Medigap Open Enrollment Period generally lasts six months, beginning the first month someone is both 65 or older and enrolled in Part B. During that protected period, an insurer cannot deny a policy or change its price because of health problems.

Medical underwriting is an insurer’s review of an applicant’s health history. Outside a protected enrollment or guaranteed-issue period, an insurer may use that information to decide whether to sell a policy and what to charge, subject to state law.

States can provide stronger protections, including additional opportunities for people under 65 or annual chances to change policies. That is why ZIP code and state rules matter.

Federal rules include two important first-year protections:

• If someone drops a Medigap policy to join Medicare Advantage for the first time, they generally have 12 months to return to the former Medigap policy if the same insurer still sells it. If it is unavailable, certain other policies may be available.
• If someone joins Medicare Advantage when first eligible for Medicare Part A at 65, they can generally return to Original Medicare during the first year and buy a Medigap policy sold in their state under the applicable trial-right rules.

These protections are not a permanent undo button. Confirm the exact right, policy options, application window, and effective dates before leaving Medicare Advantage.

A Medigap premium is paid in addition to the Part B premium and any separate Part D premium. Prices can vary by carrier, policy letter, age, location, tobacco use, household discounts, and the rating method permitted by the state.

KFF’s 2026 analysis shows substantial variation across states and policy types. Treat national averages as context—not as a quote for one household—and compare the same plan letter across multiple insurers.

KFF: Medigap enrollment and premium facts

• Is this person in Original Medicare or Medicare Advantage today?
• Are they currently inside a Medigap protected period, trial right, or guaranteed-issue situation?
• Which exact plan letter is being compared, and what does it leave unpaid?
• How is the premium rated, and can it increase as the person gets older?
• Will separate Part D coverage be needed?
• Has a SHIP counselor or State Insurance Department confirmed the applicable state rules?

Do not cancel existing Medigap coverage until the replacement coverage and effective date are confirmed in writing.