What's the Best Medigap Plan? A Clear Guide for Medicare Beneficiaries

If you've recently enrolled in Medicare or are approaching 65, you've probably noticed that Original Medicare — Parts A and B — doesn't cover everything. Hospital stays, doctor visits, and outpatient procedures can still leave you with significant bills. That's where Medicare Supplement Insurance, commonly called Medigap, comes in. These private insurance policies are designed to fill the gaps left by Original Medicare, and choosing the right one can mean the difference between predictable monthly premiums and unexpected four-figure medical bills.

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. What differs is the monthly premium, which can vary dramatically — sometimes by $100 or more per month for identical coverage — depending on the insurer, your age, your gender, whether you smoke, and the state you live in. That standardization is actually good news: once you understand what each lettered plan covers, you can shop purely on price and company reputation.

For most new Medicare enrollees in 2025 and 2026, the conversation about Medigap starts and ends with two plans: Plan G and Plan N. Plan C and Plan F — which were the most popular plans for years because they covered the Part B deductible — are no longer available to people who became eligible for Medicare on or after January 1, 2020. If you were already enrolled in Plan F before that date, you can keep it, but new enrollees must look elsewhere. Plan G has effectively become the new gold standard. 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 annual Part B deductible, which is $257 in 2025. Once you pay that deductible yourself at the start of each year, Plan G covers 100% of Medicare-approved costs for the rest of the year.

Plan N is the other major contender, and it's worth serious consideration if you're in relatively good health and want to keep your monthly premiums lower. Plan N covers the same broad categories as Plan G, including the Part A deductible, but it 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 can legally charge. More importantly for day-to-day use, Plan N requires you to pay copays of up to $20 for office visits and up to $50 for emergency room visits that don't result in a hospital admission. If you rarely see doctors and live in a state where most physicians accept Medicare assignment — which means they agree not to charge excess fees — Plan N can save you $30 to $80 per month in premiums compared to Plan G, potentially adding up to nearly $1,000 in annual savings. However, if you have chronic conditions requiring frequent specialist visits, those $20 copays can accumulate quickly and erode the premium savings.

Plan K and Plan L are cost-sharing plans that cover only a percentage of most benefits — 50% and 75%, respectively — in exchange for significantly lower premiums. They also come with annual out-of-pocket limits ($7,220 for Plan K and $3,610 for Plan L in 2025), which provides a ceiling on your exposure. These plans are rarely the best choice for most beneficiaries because the unpredictability of cost-sharing can be stressful on a fixed income, but they may appeal to very healthy enrollees who want catastrophic-style protection at the lowest possible premium. Plan D and Plan M are less commonly sold and occupy a middle ground that most beneficiaries find less compelling than G or N. High-deductible versions of Plan G and Plan F also exist — you pay all costs until you reach a deductible of $2,870 in 2025, after which the plan covers everything. These high-deductible plans carry very low monthly premiums, sometimes under $50, but require financial discipline and a willingness to absorb significant costs in a bad health year.

Timing your Medigap enrollment is just as important as choosing the right plan. The most protected window is your Medigap Open Enrollment Period, a one-time, six-month window that begins the first month you are both 65 or older and enrolled in Medicare Part B. During this period, federal law guarantees you the right to buy any Medigap plan sold in your state — regardless of your health history. Insurers cannot reject your application, charge you more because of a pre-existing condition, or make you wait for coverage to begin. Once this window closes, you generally lose those guaranteed issue rights, and insurers in most states can use medical underwriting to deny you coverage or charge higher premiums based on your health status. This makes it critical not to delay Part B enrollment without a valid reason, such as having employer-sponsored coverage through active employment.

State rules add another layer of complexity. A handful of states have enacted consumer protections that go beyond federal minimums. New York and Massachusetts, for example, require insurers to sell Medigap plans on a guaranteed issue basis year-round, regardless of health status — a significant advantage for residents of those states who may have missed their initial enrollment window or want to switch plans later. Thirteen states have what's known as a birthday rule, which gives beneficiaries a 30-day window each year around their birthday to switch to a Medigap plan with equal or lesser benefits without medical underwriting. Those states are California, Idaho, Illinois, Kentucky, Louisiana, Maine, Maryland, Missouri, Nevada, New Jersey, New York, Oklahoma, and Oregon. If you live in one of these states and feel locked into a plan that no longer suits you, your annual birthday window may be your opportunity to make a change.

Premium pricing structures also vary by insurer and deserve attention when comparing quotes. 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 the age at which you first buy the policy and don't increase as you age. Attained-age-rated plans — the most common type — start lower but increase as you get older, which can make them significantly more expensive by your late 70s and 80s. When comparing two plans with similar monthly premiums today, ask the insurer which rating method they use, because the long-term cost difference can be substantial.

To find the best price for the plan you've chosen, use Medicare's official Plan Finder tool at Medicare.gov or contact your State Health Insurance Assistance Program, known as SHIP. SHIP counselors provide free, unbiased help comparing Medigap plans in your area and can walk you through the enrollment process 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-MEDICARE. Getting at least three to five quotes for the same lettered plan from different insurers is a practical step that can yield meaningful savings — sometimes hundreds of dollars per year — for identical coverage.