If you've spent any time researching Medicare Supplement insurance — commonly called Medigap — you've probably noticed that the question 'which plan is best?' gets answered differently depending on who you ask. An insurance agent might steer you toward the plan that pays the highest commission. A friend might swear by whatever plan they picked. But the honest answer is that the best Medigap plan depends on your health, your finances, and how much financial uncertainty you can tolerate. What follows is a clear-eyed breakdown of how these plans actually work, what they cost, and where people commonly go wrong.
Medigap plans are standardized by the federal government, which means a Plan G sold by Aetna covers exactly the same benefits as a Plan G sold by Mutual of Omaha or Blue Cross Blue Shield. There are currently ten standardized plan types labeled A, B, D, G, K, L, M, N, and two high-deductible variants (Plan G-HD and Plan F-HD). Plan C and Plan F are no longer available to people who became eligible for Medicare on or after January 1, 2020, because federal law eliminated plans that cover the Part B deductible for new enrollees. If you became eligible before that date, you may still be able to purchase Plan F, but for most people reading this, the real decision comes down to Plan G, Plan N, or one of the high-deductible options.
Plan G is the gold standard for comprehensive coverage in 2025 and 2026. It covers Medicare Part A coinsurance and hospital costs, Part B coinsurance or copayments, the first three pints of blood, Part A hospice care coinsurance, skilled nursing facility coinsurance, the Part A deductible ($1,676 in 2025), and foreign travel emergency care up to plan limits. The only thing Plan G does not cover is the Part B deductible, which is $257 in 2025. That means after you pay that $257 once per year, Medicare and your Medigap plan together cover 100% of Medicare-approved charges for the rest of the year. For someone managing a chronic condition, seeing multiple specialists, or simply wanting to know exactly what their healthcare will cost, Plan G delivers genuine peace of mind. Monthly premiums for Plan G vary widely — you might pay $120 per month in a rural Midwestern state or $280 per month in a high-cost urban area like New York City or San Francisco — but the coverage is identical regardless of what you pay.
Plan N is the second most popular choice, and it's worth understanding precisely where it differs from Plan G. With Plan N, you still pay the $257 Part B deductible, just like with Plan G. But Plan N also exposes you to copays of up to $20 for office visits and up to $50 for emergency room visits that don't result in an inpatient admission. Critically, Plan N does not cover Part B excess charges — the additional amount (up to 15% above Medicare's approved rate) that doctors who don't accept Medicare assignment are legally allowed to bill you. In states where excess charges are common, or if you see specialists who don't accept Medicare assignment, Plan N can leave you with unexpected bills. The trade-off is that Plan N premiums are typically 15% to 25% lower than Plan G premiums for the same age and location. If you're in good health, rarely visit specialists, and live in a state where most physicians accept Medicare assignment, Plan N may save you real money over time. But if you end up needing frequent medical care, those copays accumulate, and the savings can evaporate.
High-deductible Plan G deserves more attention than it typically gets. With Plan G-HD, you pay the same premiums as a much cheaper plan — often $40 to $70 per month — but you must meet a high deductible ($2,870 in 2025) before the plan begins paying. After that deductible is met, coverage is identical to standard Plan G. This option makes the most financial sense for people who are healthy, have sufficient savings to cover the deductible in a bad year, and want to keep monthly costs low while still having a backstop against catastrophic expenses. Think of it as a high-deductible health plan equivalent within the Medicare world. Over five years of good health, the premium savings compared to standard Plan G can easily exceed $5,000 — money that stays in your pocket unless you have a serious illness or injury.
The single most important thing to understand about buying Medigap is the enrollment timing. When you first enroll in Medicare Part B and are 65 or older, you have a six-month Medigap Open Enrollment Period during which insurers cannot deny you coverage or charge you more based on your health history. This is a federally guaranteed right, and it is the only time most people in most states have it. If you miss this window and try to buy Medigap later — say, at age 70 after dropping a Medicare Advantage plan — insurers in most states can subject you to medical underwriting, meaning they can reject your application or charge significantly higher premiums based on pre-existing conditions like diabetes, heart disease, or a history of cancer. This is not a hypothetical risk. It happens regularly, and it leaves people locked into coverage they don't want or unable to get the coverage they need.
There are specific situations that trigger a guaranteed issue right outside of your initial enrollment window. If you lose employer-sponsored coverage, if your Medicare Advantage plan leaves your service area or loses its Medicare contract, or if you move out of your plan's service area, you may qualify for a Special Enrollment Period that includes guaranteed issue rights for certain Medigap plans. These rights are narrower than your initial open enrollment rights — they typically apply to Plans A, B, D, G, K, and L — so it's important to understand exactly what you qualify for before making any coverage changes. CMS publishes detailed guidance on guaranteed issue rights at Medicare.gov.
Thirteen states have enacted birthday rules that give beneficiaries an additional annual window to switch Medigap plans without medical underwriting. Those states are California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon. The birthday rule typically gives you a 30-day window around your birthday each year to switch to a plan with equal or lesser benefits from any insurer, without answering health questions. If you live in one of these states and feel you're overpaying for your current Medigap plan, your birthday window is an opportunity to shop for lower premiums for identical coverage. New York and Connecticut go further, offering year-round guaranteed issue rights for Medigap, which is why premiums in those states tend to be higher — insurers can't price out sick people, so they spread the risk across everyone.
Premium pricing structures are another area where people make expensive long-term mistakes. Medigap insurers use three different methods to set premiums. Community-rated plans charge everyone the same premium regardless of age — your premium may increase over time due to inflation, but not because you're getting older. Issue-age-rated plans set your premium based on your age when you first buy the policy, and that rate doesn't increase as you age, though it may increase for other reasons. Attained-age-rated plans start with lower premiums but increase as you get older, often becoming significantly more expensive in your 70s and 80s when you're least able to afford the jump and least able to switch plans due to medical underwriting. A plan that looks like a bargain at 65 on an attained-age basis may cost twice as much by the time you're 80. When comparing plans, always ask the insurer which pricing method they use and request projected premium schedules for future years.
One comparison that trips up many beneficiaries is Medigap versus Medicare Advantage. These are fundamentally different approaches to covering your healthcare costs. Medicare Advantage (Part C) replaces Original Medicare with a private plan that typically includes prescription drug coverage and extra benefits like dental and vision, often for low or no additional premium. But Medicare Advantage plans use networks, require prior authorizations, and expose you to copays and out-of-pocket maximums that can reach $9,350 for in-network care in 2025. Medigap works alongside Original Medicare, giving you access to any doctor or hospital that accepts Medicare anywhere in the country, with predictable costs. For people who travel frequently, have complex medical needs, or simply want maximum flexibility, Medigap paired with a standalone Part D drug plan often provides more reliable access to care — though it typically costs more in monthly premiums than a $0-premium Medicare Advantage plan.
When it comes to actually shopping for a Medigap plan, the most useful tool available is the Medicare Plan Finder at Medicare.gov, which allows you to compare plans available in your ZIP code. Because the benefits are standardized, you should be comparing only on price, the insurer's financial stability rating (look for A-rated carriers from AM Best), and the insurer's history of premium increases. Your State Health Insurance Assistance Program, known as SHIP, offers free, unbiased counseling from trained volunteers who can walk you through your options without trying to sell you anything. You can find your local SHIP contact through the Eldercare Locator at eldercare.acl.gov or by calling 1-800-677-1116. These counselors are particularly valuable if you're approaching your initial enrollment window and feeling overwhelmed by the choices.
Finally, it's worth being honest about what Medigap does not cover. Standard Medigap plans do not include prescription drug coverage — you'll need a separate Part D plan for that. They don't cover routine dental, vision, or hearing care. They don't cover long-term custodial care in a nursing home. And while Plan G covers foreign travel emergency care up to a $50,000 lifetime limit (after a $250 deductible), it is not a substitute for comprehensive travel insurance if you spend significant time abroad. Understanding these gaps helps you build a complete coverage picture rather than assuming Medigap handles everything Original Medicare doesn't.