How to Choose a Medigap Plan: Comparing Plans A Through N

Choosing a Medigap plan is one of the most consequential decisions you will make when setting up your Medicare coverage. The right plan can protect you from thousands of dollars in unexpected medical costs. The wrong one could leave you overpaying for coverage you do not need.

With 10 standardized plan letters, dozens of insurance carriers in every state, and three different pricing methods, the landscape can feel overwhelming. This guide breaks down every plan option, compares benefits, explains how premiums work, and walks you through the enrollment rules you need to know.

What Is Medigap?

Medigap, formally known as Medicare Supplement Insurance, is a private health insurance policy that supplements Original Medicare. With Original Medicare alone, you are responsible for deductibles, coinsurance, and copayments, and there is no annual out-of-pocket maximum. A Medigap plan fills those gaps by paying some or all of the cost-sharing that Original Medicare leaves behind.

When you visit a doctor or hospital, Medicare pays its share first. The remaining balance is then sent to your Medigap insurer, which pays according to your plan's benefits. You retain the freedom to see any doctor or hospital that accepts Medicare nationwide, with no networks, referrals, or prior authorization. Medigap only works with Original Medicare, covers one person per policy, does not include prescription drug coverage, and is guaranteed renewable as long as you pay your premiums.

The 10 Standardized Medigap Plans

Federal law standardizes Medigap into 10 letter-designated plans: A, B, C, D, F, G, K, L, M, and N. Each plan letter offers a defined set of benefits that is identical regardless of which insurance company sells it. The only differences between carriers are the premium, financial strength, customer service, and available discounts. Massachusetts, Minnesota, and Wisconsin use their own standardized structures.

Important: Plans C and F are closed to anyone who became newly eligible for Medicare on or after January 1, 2020. The Medicare Access and CHIP Reauthorization Act (MACRA) of 2015 prohibited selling Medigap plans that cover the Part B deductible to new beneficiaries. Those already eligible before that date can still purchase or keep Plans C and F.

• Plan A: Basic benefits only. Covers Part A coinsurance, Part B coinsurance, hospice coinsurance, and the first three pints of blood.
• Plan B: Plan A benefits plus the Part A hospital deductible ($1,676 per benefit period in 2025).
• Plan C (closed after 2020): Comprehensive coverage including both deductibles, SNF coinsurance, and foreign travel emergencies.
• Plan D: Part A deductible, SNF coinsurance, and foreign travel emergencies. Same as Plan G but without Part B excess charge coverage.
• Plan F (closed after 2020): The former gold standard. Covers everything including both deductibles, all coinsurance, excess charges, and foreign travel. A high-deductible version exists.
• Plan G: The new gold standard. Everything Plan F covers except the Part B deductible ($257 in 2025). A high-deductible version is available ($2,870 deductible in 2025).
• Plan K: 50% cost-sharing on most benefits with an annual out-of-pocket limit ($7,060 in 2025). After the limit, the plan pays 100%.
• Plan L: 75% cost-sharing with a lower out-of-pocket limit ($3,530 in 2025). A middle ground between full-coverage and cost-sharing plans.
• Plan M: Covers 50% of the Part A deductible plus basic benefits, SNF coinsurance, and foreign travel emergencies. Less commonly offered.
• Plan N: The second most popular plan. Covers Part A deductible, SNF coinsurance, and foreign travel. Requires copays of up to $20 for office visits and up to $50 for non-admitted ER visits. Does not cover Part B excess charges. Premiums run 15% to 30% lower than Plan G.

What Each Plan Covers

All 10 plans draw from nine benefit categories. The difference between plans is how much of each benefit they cover.

• Part A coinsurance and hospital costs: Covered by every plan at 100% (Plans K and L at 50% and 75%). Includes up to 365 additional days after Medicare benefits are exhausted.
• Part B coinsurance: Plans A, B, C, D, F, G, and M cover at 100%. Plan N covers at 100% with copays. Plans K and L cover at 50% and 75%.
• Blood (first three pints): Covered by all plans. Plans K and L cover at 50% and 75%; all others at 100%.
• Hospice care coinsurance: Covered by every plan. Plans K and L at 50% and 75%; all others at 100%.
• SNF coinsurance: Days 21 through 100 ($204.50 per day in 2025). Covered at 100% by Plans C, D, F, G, M, and N. Plan K at 50%, Plan L at 75%. Plans A and B do not cover it.
• Part A deductible: Covered at 100% by Plans B, C, D, F, G, and N. Plan K at 50%, Plan L at 75%, Plan M at 50%. Plan A does not cover it.
• Part B deductible: Only covered by Plans C and F, which is why they are closed to new enrollees.
• Part B excess charges: Only Plans F and G cover these. Excess charges occur when a doctor charges up to 15% above Medicare's approved amount. Over 97% of physicians accept assignment, making this uncommon.
• Foreign travel emergency: Covers 80% of emergency costs abroad after a $250 deductible, up to $50,000 lifetime. Plans C, D, F, G, M, and N include it. Plans A, B, K, and L do not.

Most Popular Plans: G and N

Since Plan F was closed to new beneficiaries, the market has consolidated around Plan G and Plan N. Together they account for the vast majority of new enrollments.

Plan G is the gold standard for new enrollees. It covers every benefit category except the annual Part B deductible. Once you pay that deductible, your out-of-pocket exposure is essentially zero. There are no copays, no coinsurance, and no surprise bills for covered services. Plan G is ideal for beneficiaries with chronic conditions, those who see multiple specialists, or anyone who wants maximum cost predictability.

Plan N is the budget alternative. It covers the same benefits as Plan G but requires copays of up to $20 for some office visits and up to $50 for ER visits that do not result in admission, and does not cover Part B excess charges. Plan N premiums typically run 15% to 30% lower, saving $360 to $720 per year. For healthy people who visit the doctor infrequently, those savings easily outweigh the modest copays.

The choice comes down to your personal health profile and tolerance for cost-sharing. Plan G suits those who want near-complete coverage. Plan N suits healthy enrollees who prioritize premium savings and can tolerate small out-of-pocket costs at the point of care.

How Much Do Medigap Plans Cost?

Premiums vary significantly by plan, location, age, gender, and insurer. Even for the same plan letter in the same zip code, premiums from different carriers can differ by $50 or more per month. Here are general monthly ranges for a 65-year-old:

• Plan A: $75 to $175
• Plan B: $100 to $200
• Plan D: $110 to $220
• Plan F (grandfathered): $180 to $350+, often higher than Plan G because the remaining pool is older
• Plan G: $120 to $250, national average around $145 to $170
• Plan N: $90 to $190, usually 15% to 30% less than Plan G
• High-Deductible Plan G: $40 to $80, but you must meet a $2,870 deductible (2025) first

Several factors influence your individual premium. Age is the primary driver, since most policies use attained-age pricing. Location matters because healthcare costs vary by region; states like Florida and New York tend to have higher premiums than Idaho or Iowa. Tobacco use can add 10% to 25% to your rate. Gender also affects pricing in some states. Finally, many insurers offer discounts for household members, non-smokers, electronic fund transfer payments, or paying annually.

Three Medigap Pricing Methods

How an insurer prices its Medigap policies has a major impact on what you pay over the lifetime of your coverage. Understanding the three methods helps you avoid policies that start cheap but become unaffordable as you age.

1. Community-rated (no-age-rated): Everyone pays the same base premium regardless of age. Premiums may rise due to inflation but not because you get older. Starting premiums are often higher, but long-term cost stability is the best of the three methods.
2. Issue-age-rated: Your premium is based on your age when you first buy the policy. It does not increase due to aging but can rise for other reasons. The younger you buy, the lower your base rate. A solid middle-ground option.
3. Attained-age-rated: The most common method. Premiums start based on your current age and increase automatically as you age, on top of general rate increases. Offers the lowest premiums at 65 but can become expensive in your 70s and 80s. A policy costing $120 per month at 65 might reach $250 or more by age 80.

Always ask which pricing method an insurer uses. If you plan to keep your policy for decades, a community-rated or issue-age-rated policy may save thousands over time compared to attained-age, even if the starting premium is slightly higher.

When to Enroll: The Medigap Open Enrollment Period

Timing is the single most important factor in purchasing a Medigap plan. Federal law provides a one-time, six-month Medigap Open Enrollment Period that begins the first day of the month when you are both 65 or older and enrolled in Medicare Part B. This is the only time you are guaranteed the right to buy any Medigap plan in your state, regardless of health status.

During this window, insurers cannot deny your application, cannot charge more because of health problems, and must accept you for any plan they sell. A waiting period of up to six months may apply for pre-existing conditions, but you cannot be refused coverage. For example, if you turn 65 in June 2026 and Part B starts June 1, your window runs June 1 through November 30, 2026.

Guaranteed issue rights also apply outside this window in specific situations: your Medicare Advantage plan leaves your area, you leave Medicare Advantage within 12 months to return to Original Medicare, your Medigap insurer goes bankrupt, or you dropped Medigap to try Medicare Advantage for the first time and want to return within 12 months.

If you miss your Open Enrollment Period and do not qualify for guaranteed issue, insurers can use full medical underwriting. They may deny your application, charge higher premiums, or impose exclusion periods. If you have developed health problems since turning 65, obtaining a Medigap policy may be very difficult or prohibitively expensive. This is why virtually every Medicare advisor recommends enrolling during the initial window.

How to Compare Plans

Because Medigap benefits are standardized, comparing plans is really about comparing insurance companies. Here is a systematic approach to choosing the right insurer for your chosen plan letter.

• Check AM Best ratings: AM Best evaluates insurers on their ability to pay claims. Ratings of A or higher indicate strong financial stability. You may hold this policy for 20 to 30 years, so the company's long-term strength matters.
• Review the NAIC complaint index: The National Association of Insurance Commissioners publishes a complaint index for each insurer. A score of 1.0 is average; below 1.0 means fewer complaints than expected. This reveals customer service issues that premium quotes alone cannot.
• Compare premiums from multiple insurers: Get quotes from at least three to five companies. The cheapest premium is not always the best; a company with modest, predictable rate increases may be a better long-term value than one that starts low but raises rates aggressively.
• Ask about discounts: Household discounts (5% to 12%), non-smoker discounts, EFT payment discounts, and annual payment discounts are common. Always ask before finalizing.
• Investigate rate increase history: Ask for the company's rate increase history over the past five to ten years. Companies that raise rates by 3% to 5% annually are generally more stable than those that hold flat and then impose large increases. Your state's Department of Insurance may have historical rate filings online.

Can You Switch Medigap Plans Later?

You can apply to switch Medigap plans at any time, but outside your initial Open Enrollment Period or a guaranteed issue situation, the new insurer can use medical underwriting. You could be denied, charged more, or subjected to a waiting period based on your health. Common reasons for denial include recent cancer treatment, insulin-dependent diabetes, COPD requiring oxygen, and certain heart conditions.

Federal guaranteed issue rights apply in certain situations even after your initial period, such as when a Medicare Advantage plan leaves your area, your Medigap insurer goes bankrupt, or your employer coverage ends. In these cases, insurers must sell you a policy without health screening.

Several states offer additional protections. The birthday rule, used in California, Oregon, Illinois, and Louisiana, gives you a window around your birthday each year to switch to a plan with equal or lesser benefits without underwriting. Other states, including Connecticut, Maine, Massachusetts, and New York, offer continuous or annual open enrollment. Check with your state's Department of Insurance or a SHIP counselor to understand your specific rights.

Medigap vs Medicare Advantage

Before finalizing your Medigap decision, it is worth understanding how it compares to Medicare Advantage. These are two fundamentally different approaches to Medicare coverage, and you cannot use both at the same time.

Original Medicare with Medigap gives you nationwide provider access with no networks, no referrals, and no prior authorization. You pay a higher monthly premium (Part B plus Medigap plus Part D) but have minimal out-of-pocket costs at the point of care. With Plan G, your annual exposure is limited to the Part B deductible. This path is ideal for travelers, those with chronic conditions, and anyone who values cost predictability.

Medicare Advantage replaces Original Medicare with a private plan that often bundles drug, dental, vision, and hearing benefits. Many plans have zero or low monthly premiums beyond Part B. However, they use provider networks, may require prior authorization, and have out-of-pocket maximums that can reach $8,300 or more per year. This works well for healthy people who use local providers and want lower premiums.

The most critical trade-off: if you choose Medicare Advantage and later want to switch to Original Medicare with Medigap, you will likely face medical underwriting. If you have developed health conditions, you may be denied coverage entirely. A 12-month trial right exists for first-time Medicare Advantage enrollees, but beyond that window, switching back becomes much harder. This makes the initial decision at 65 particularly consequential.

The Bottom Line

Choosing the right Medigap plan comes down to balancing coverage breadth against monthly cost and understanding the enrollment rules. For most new Medicare beneficiaries, the decision is between Plan G and Plan N. Plan G provides near-total coverage and maximum cost predictability. Plan N offers strong coverage with lower premiums and minor copays. Either plan, paired with Original Medicare and a Part D drug plan, provides comprehensive protection with the freedom to see any Medicare-accepting provider nationwide.

The most important step is to enroll during your Medigap Open Enrollment Period. This six-month window is your best and often only opportunity to purchase at standard rates with guaranteed acceptance. Start researching at least two to three months before your 65th birthday. Compare premiums from multiple insurers, ask about pricing methods and discounts, and check each company's financial strength through AM Best and complaint record through the NAIC.

If you are unsure which plan to choose, contact your local SHIP (State Health Insurance Assistance Program) for free, unbiased counseling. SHIP counselors can help you compare plans, understand your state's specific rules, and make an informed decision. Whatever you choose, securing a Medigap policy during your initial enrollment window is one of the smartest financial decisions you can make as you enter Medicare.