Medicare Covers 80%. Medigap Covers the Rest. Here’s Which Plan Is Worth Buying in 2026 — and When You Must Act.

WASHINGTON, May 3, 2026 —

Key Takeaways

• Medicare covers approximately 80% of approved outpatient costs — leaving the remaining 20% as your responsibility with no annual out-of-pocket cap under original Medicare, meaning a serious illness could cost a beneficiary tens of thousands of dollars in a single year without supplemental coverage.
• Plan G has replaced Plan F as the most comprehensive Medigap option available to new enrollees since January 2020 — covering everything Plan F covered except the $240 Part B deductible, making it the gold standard for beneficiaries who want predictable healthcare costs in retirement.
• The Medigap open enrollment window — the six months beginning the month you turn 65 and enroll in Medicare Part B — is the only period during which insurers are legally required to sell you any Medigap plan at standard rates regardless of your health history. Miss this window and you can be denied coverage or charged significantly more.

What Medicare Actually Doesn’t Cover — and Why That Gap Is Dangerous

Original Medicare — the federal program consisting of Part A for hospital coverage and Part B for outpatient care — is comprehensive in what it covers but deliberately incomplete in what it pays. The design was intentional: Congress built cost-sharing into Medicare specifically to discourage overutilization by requiring beneficiaries to have skin in the game financially.

The problem is that the cost-sharing amounts, which made sense when Medicare was designed in 1965, have grown in ways that can be financially catastrophic for retirees on fixed incomes.

Under Part A in 2026, a hospital stay requires a $1,676 deductible for each benefit period — not per year, but per benefit period, meaning if you are hospitalized twice with a gap of more than 60 days between stays, you pay the deductible twice. Days 61 through 90 of a hospital stay cost $419 per day in coinsurance. Days 91 and beyond deplete your lifetime reserve days at $838 per day.

Under Part B in 2026, after the $240 annual deductible, Medicare pays 80% of approved charges. You pay 20% — with no cap. A single outpatient surgery, chemotherapy course, or extended physical therapy program can generate 20% cost-sharing that runs to thousands of dollars per month. Medicare does not have a maximum out-of-pocket limit under original coverage. You are exposed to unlimited liability.

Medigap exists to fill these gaps. Depending on the plan you choose, it can eliminate virtually all of this exposure.

The 2026 Medigap Plans — What Each One Covers

Federal law standardizes Medigap plans by letter. Every insurer selling Plan G must offer identical benefits — the only difference between carriers is price, financial strength, and customer service. This standardization makes comparison straightforward.

Plan F — which also covered the Part B deductible — was eliminated for new Medicare enrollees beginning January 1, 2020. If you turned 65 before that date and enrolled in Plan F, you can keep it. New enrollees cannot purchase it.

Plan G vs Plan N — The Only Two Plans Worth Serious Consideration

For the vast majority of new Medicare enrollees in 2026, the choice narrows to two plans.

Plan G is the most comprehensive option available. It covers everything Medicare leaves behind except the $240 Part B annual deductible. After you pay that deductible once per year, Plan G picks up 100% of the remaining Medicare-approved costs — all Part B coinsurance, all Part A coinsurance, the Part A deductible, and Part B excess charges. There are no copays, no surprise bills, and no annual out-of-pocket maximum to track because your exposure is essentially capped at $240 per year.

The average monthly premium for Plan G at age 65 runs approximately $120 to $180 in most markets — varying by state, insurer, and rating methodology. At $150 per month, the annual premium is $1,800. Add the $240 deductible and your total known annual healthcare cost exposure under original Medicare plus Plan G is $2,040. Every medical expense above that is covered.

Plan N offers the same core protections as Plan G — Part A and Part B coinsurance, the Part A deductible, foreign travel emergency — but with two differences. It does not cover Part B excess charges, and it charges copays of up to $20 for office visits and up to $50 for emergency room visits that do not result in admission. In exchange, Plan N premiums typically run $20 to $40 less per month than Plan G.

Plan N makes most sense for beneficiaries who see doctors infrequently, live in states where physicians cannot charge Medicare excess charges, and are comfortable with the copay structure. In states like Massachusetts, New York, Connecticut, Ohio, and Minnesota — where excess charges are prohibited or rarely applied — Plan N’s lower premium makes it the mathematically superior choice for healthy enrollees.

The Three Medigap Pricing Methods — Why Your Premium Can Double by 75

Not all Medigap plans are priced the same way, and the pricing method an insurer uses matters far more over a 20-year retirement than the initial premium.

Community-rated plans charge the same premium to all enrollees regardless of age. A 65-year-old and an 80-year-old with the same plan pay the same amount. Premiums increase only with inflation and claims experience — not with your age. These plans are typically more expensive initially but become significantly cheaper relative to alternatives as you age.

Issue-age-rated plans set your premium based on your age at the time you enroll and do not increase it as you get older. A 65-year-old locks in a rate appropriate to age 65 permanently, adjusted only for inflation. These plans reward early enrollment.

Attained-age-rated plans — the most common type — start with the lowest initial premiums but increase as you age. At 65 the premium is low and attractive. At 75 or 80 the same plan from the same insurer may cost significantly more. These plans are heavily marketed to new enrollees because the initial price looks compelling, but they carry the highest long-term cost for most beneficiaries.

The difference between choosing a community-rated or issue-age-rated plan versus an attained-age-rated plan can amount to thousands of dollars per year by the time a beneficiary reaches their mid-70s.

The Enrollment Window That Cannot Be Recovered

The six-month Medigap open enrollment period — beginning the first day of the month in which you are both 65 years old and enrolled in Medicare Part B — is protected by federal law. During this window, no insurer can deny you coverage, charge you a higher premium based on health status, or impose a waiting period for pre-existing conditions.

Outside this window, Medigap insurers in most states have the right to apply medical underwriting. They can ask about your health history, decline to cover you, charge you significantly higher premiums, or exclude coverage for pre-existing conditions for up to six months. In 35 states, there is no guaranteed issue right after the open enrollment window closes — meaning a beneficiary who develops a serious illness before enrolling in Medigap may never be able to obtain supplemental coverage at standard rates.

The six-month window is the single most important enrollment decision most Americans make in retirement. It passes once. It cannot be recovered. And the consequences of missing it — a lifetime of potentially uninsurable medical expense exposure under original Medicare — are irreversible in most states.

Medigap vs Medicare Advantage — The Right Question to Ask

The alternative to Medigap under original Medicare is Medicare Advantage — a private insurance plan that replaces original Medicare rather than supplementing it. Advantage plans typically offer lower premiums and additional benefits but come with networks, prior authorization requirements, and cost-sharing structures that can create significant expenses for beneficiaries who are seriously ill or who frequently need specialist care.

The choice between Medigap and Medicare Advantage is not about which is better universally — it is about which fits your specific health situation, geography, and financial circumstances.

Medigap works best for beneficiaries who want maximum flexibility — seeing any doctor who accepts Medicare anywhere in the country without network restrictions — and who are willing to pay higher premiums for the predictability of near-zero out-of-pocket costs when they need care.

Medicare Advantage works best for beneficiaries who are generally healthy, who have access to good in-network providers in their area, and who can manage the administrative requirements of a private insurance plan including prior authorizations and referrals.

The critical difference that most beneficiaries discover too late: switching from Medicare Advantage back to original Medicare with Medigap coverage after age 65 requires passing medical underwriting in most states. A beneficiary who tries Medicare Advantage at 66, develops a serious condition at 68, and then wants to switch to Medigap may find they cannot get coverage at standard rates. The Medigap open enrollment window at 65 is the only guaranteed entry point.

Pro Tips a Generic Article Would Miss

1. The household discount is one of the most consistently overlooked savings in Medigap. Most insurers offer discounts of 5% to 12% when two spouses or domestic partners in the same household both enroll in Medigap plans with the same company. On two Plan G premiums totaling $3,600 per year, a 10% household discount saves $360 annually — compounding over a 20-year retirement to more than $7,000. Always ask for the household discount explicitly. Agents rarely volunteer it.

2. The High-Deductible Plan G is a legitimate option for healthy new enrollees who want catastrophic protection at a minimal premium. High-Deductible Plan G requires the beneficiary to pay a $2,870 deductible in 2026 before coverage kicks in — but after that threshold is met, the plan covers everything Plan G normally covers. The premium runs approximately $40 to $70 per month — roughly $100 less than standard Plan G. For a 65-year-old in excellent health who expects minimal healthcare use, the math can favor High-Deductible Plan G for the first several years of retirement while preserving the option to switch during future guaranteed issue periods.

3. If you missed your open enrollment window but your spouse is turning 65, help them avoid your mistake. The Medigap open enrollment window applies individually to each Medicare beneficiary at the time they turn 65. A spouse who missed the window does not affect the other spouse’s protected enrollment window. If your partner is approaching 65, the decisions they make in the six months following their Medicare Part B enrollment date will determine their Medigap access for life.

The single most important retirement healthcare decision you will make is not which Medicare plan to choose — it is whether to act during your six-month Medigap open enrollment window before it closes permanently. Contact a licensed independent Medicare broker in your state — one who represents multiple carriers rather than a single company — and ask them to run side-by-side premium comparisons for Plan G and Plan N from at least three carriers, showing you both the community-rated and attained-age pricing structures. That comparison, done before your 65th birthday, is the difference between a retirement where healthcare costs are predictable and one where a serious illness can erase years of savings.

Frequently Asked Questions

Q: What is Medigap and how is it different from Medicare Advantage? A: Medigap is a supplemental insurance policy that works alongside original Medicare — it pays the costs Medicare leaves behind, such as the 20% Part B coinsurance and Part A deductibles. Medicare Advantage replaces original Medicare entirely with a private insurance plan. The two cannot be used together.

Q: Which Medigap plan is best in 2026? A: For most new enrollees, Plan G offers the most comprehensive coverage — paying all Medicare cost-sharing except the $240 Part B annual deductible. Plan N costs less but requires copays and does not cover Part B excess charges. High-Deductible Plan G is suitable for healthy enrollees who want catastrophic protection at a lower premium.

Q: How much does Medigap cost per month in 2026? A: Premiums vary by age, state, insurer, and pricing method. The average Plan G premium for a 65-year-old ranges from $120 to $180 per month. Plan N runs approximately $20 to $40 less. High-Deductible Plan G runs approximately $40 to $70 per month.

Q: Can I be denied Medigap coverage? A: During your six-month open enrollment window — the six months following the month you turn 65 and enroll in Medicare Part B — no insurer can deny you coverage or charge more based on health status. Outside that window, insurers in most states can apply medical underwriting and may deny coverage or charge higher premiums.

Q: Is Medigap worth the extra cost? A: For beneficiaries who use Medicare regularly, Plan G typically pays for itself with one or two hospitalizations or significant outpatient procedures per year. For very healthy beneficiaries who rarely use healthcare, High-Deductible Plan G provides catastrophic protection at a cost comparable to a monthly streaming subscription.