Medigap, also called Medicare Supplement Insurance, helps cover the gaps in Original Medicare—the deductibles, coinsurance, and copays that can add up to significant out-of-pocket costs. These standardized plans, sold by private insurance companies, work alongside Original Medicare to provide more comprehensive coverage and financial predictability. Understanding Medigap is essential for anyone choosing Original Medicare over Medicare Advantage.

What Medigap Covers and How It Works

Medigap policies supplement Original Medicare by covering some or all of the cost-sharing requirements that Medicare Parts A and B leave to beneficiaries. When you have Medigap, Medicare pays its share of covered services first, then your Medigap policy pays its share. You typically pay nothing or very little out-of-pocket at the point of service.

Medigap covers critical costs including Part A coinsurance for hospital stays beyond 60 days, Part A hospice care coinsurance, the Part A deductible ($1,676 in 2025), Part B coinsurance or copayment (typically 20% of approved amounts), the first three pints of blood each year, and Part A coinsurance for skilled nursing facility care. Some plans also cover the Part B deductible ($257 in 2025) and Part B excess charges when doctors don't accept Medicare assignment.

Importantly, Medigap works with Original Medicare only—you cannot use a Medigap policy with Medicare Advantage plans. You must be enrolled in both Medicare Parts A and B to purchase Medigap. These policies don't cover prescription drugs, so you'll need a separate Part D plan, nor do they cover dental, vision, hearing aids, or long-term care.

One of Medigap's greatest advantages is provider freedom. With Medigap and Original Medicare, you can see any doctor or specialist in the United States who accepts Medicare, without networks, referrals, or prior authorization. This flexibility proves especially valuable for people who travel frequently, split time between different locations, or want access to specialized care at specific institutions.

10 Standardized Medigap Plans Explained

Federal law standardizes Medigap plans, meaning Plan G from one insurance company provides the same basic benefits as Plan G from any other company (though premiums differ). This standardization simplifies comparison shopping—you compare prices for identical coverage. In most states, 10 standardized plans are available: A, B, C, D, F, G, K, L, M, and N.

Plan A is the most basic Medigap plan, covering Part A coinsurance for extended hospital stays, Part B coinsurance, blood, and Part A hospice coinsurance. Plan A leaves significant gaps, including both Part A and Part B deductibles, making it less popular than more comprehensive options.

Plans C and F offer the most comprehensive coverage, including Part B excess charges, Part A and Part B deductibles, and all coinsurance. However, these plans are no longer available to people who became Medicare-eligible after January 1, 2020. If you were Medicare-eligible before that date, you can still purchase or keep these plans.

Plan G is now the most comprehensive Medigap plan available to new Medicare beneficiaries. It covers everything except the Part B deductible ($257 in 2025), providing excellent coverage with minimal out-of-pocket costs. Plan G has become the most popular choice for new enrollees seeking comprehensive protection.

Plan N offers nearly as much coverage as Plan G but requires copays of up to $20 for office visits and up to $50 for emergency room visits (waived if admitted). Plan N also doesn't cover Part B excess charges. The trade-off is significantly lower premiums—typically $30-50 less monthly than Plan G.

High-Deductible Plan G features lower monthly premiums but requires you to pay a $2,870 deductible in 2025 before the plan begins paying benefits. After meeting the deductible, it covers the same benefits as standard Plan G. This option works well for healthy people who want catastrophic coverage protection at lower monthly costs.

Plans K and L are lower-premium options that cover 50% (Plan K) or 75% (Plan L) of most benefits, with out-of-pocket maximums of $7,060 (Plan K) and $3,530 (Plan L) in 2025. These plans provide some cost protection at lower monthly premiums but leave more predictable out-of-pocket costs than comprehensive plans.

Plan G vs. Plan N: Detailed Comparison

Most Medicare beneficiaries choosing Medigap select either Plan G or Plan N, making understanding the differences between these plans essential. The decision primarily comes down to balancing premium costs against potential out-of-pocket expenses.

Coverage Differences: Plan G covers all Medicare cost-sharing except the Part B deductible. Once you pay the $257 Part B deductible in 2025, you typically have no further out-of-pocket costs for Medicare-covered services. Plan N covers the same benefits but requires copays of up to $20 for office visits and up to $50 for emergency room visits (unless you're admitted). Plan N also doesn't cover Part B excess charges, which apply when doctors don't accept Medicare assignment and charge up to 15% more than Medicare's approved amount.

Premium Comparison: Monthly premiums vary by location, age, insurance company, and whether the plan uses community rating, issue-age rating, or attained-age rating. On average nationally, Plan G premiums for 65-year-olds range from approximately $130 to $220 monthly, while Plan N premiums range from about $95 to $180 monthly—typically $30-50 less than Plan G.

Total Cost Analysis: To determine which plan costs less overall, estimate your annual healthcare utilization. If you average two or more doctor visits monthly (24+ annual office visits), the $20 copays under Plan N could total $480+ annually, potentially exceeding the premium savings compared to Plan G. For people with fewer doctor visits, Plan N usually costs less overall.

Part B excess charges, while rare, represent another consideration. Only about 1% of providers bill excess charges, and most states prohibit or limit them. Unless you regularly see providers who don't accept Medicare assignment, lack of excess charge coverage under Plan N likely won't significantly impact your costs.

Best Candidates for Plan G: Plan G suits people who want the most comprehensive coverage with maximum predictability, see doctors frequently for chronic conditions, prefer paying higher premiums to avoid per-visit costs, or want simplicity with minimal out-of-pocket expenses.

Best Candidates for Plan N: Plan N works well for generally healthy people with fewer doctor visits, those comfortable with modest copays to save on premiums, budget-conscious beneficiaries seeking good value, and people who understand and accept paying up to $20 per office visit and $50 per emergency room visit.

When to Buy Medigap: Open Enrollment Rights

Timing your Medigap purchase is crucial because you have guaranteed issue rights during specific periods when insurance companies cannot deny you coverage, delay coverage, or charge more due to pre-existing conditions. Missing these windows can make getting Medigap difficult or impossible if you have health issues.

Your Medigap Open Enrollment Period is the six-month period that begins the first day of the month in which you're both 65 or older and enrolled in Medicare Part B. During this window, you have guaranteed issue rights to buy any Medigap policy sold in your state, regardless of health status. Insurance companies cannot use medical underwriting to deny you coverage or charge higher premiums.

For example, if you turn 65 in June and enroll in Part B effective June 1, your Medigap Open Enrollment Period runs from June 1 through November 30. This six-month window is your best opportunity to buy Medigap. Outside this period, insurance companies can use medical underwriting, potentially denying coverage or charging significantly higher premiums if you have health conditions.

Some states offer additional consumer protections beyond federal requirements. California, for instance, allows Medigap beneficiaries to switch to plans with equal or lesser benefits within 30 days of their birthday each year without medical underwriting. New York offers guaranteed issue rights year-round. Check your state's specific Medigap rules at your state insurance department website.

Guaranteed Issue Rights: Other Times You Can Buy Medigap

Beyond your initial six-month open enrollment, certain situations give you guaranteed issue rights to purchase Medigap. These include if your Medicare Advantage plan is leaving Medicare or stops providing coverage in your area; you move out of your plan's service area; your Medigap company goes bankrupt or stops providing coverage; you lose employer group coverage through no fault of your own; or you're in a Medicare Advantage trial right period.

The trial right period applies when you first join a Medicare Advantage plan within 12 months of enrolling in Part B. If you're unhappy with Medicare Advantage, you can return to Original Medicare within 12 months and buy any Medigap policy sold in your state with guaranteed issue rights, regardless of health status.

These guaranteed issue rights come with specific time limits, usually 63 days from when your previous coverage ends. Missing these deadlines means you'll face medical underwriting to purchase Medigap, which could result in coverage denial or unaffordable premiums if you have health conditions.

Medigap Shopping Strategies

Because Medigap plans are standardized, comparison shopping focuses on finding the lowest premium for the coverage level you want. Start by deciding which plan letter (G, N, etc.) meets your needs. Then compare premiums from multiple insurance companies for that specific plan.

Premiums vary widely between companies for identical coverage. In some areas, the difference between the highest and lowest Plan G premium exceeds $100 monthly—$1,200+ annually for identical benefits. Use medicare.gov/medigap-supplemental-insurance-plans to compare all available policies in your area.

Understand premium rating methods. Community-rated (no age rating) policies charge everyone the same premium regardless of age. Issue-age-rated policies base premiums on your age when you buy the policy and don't increase due to aging. Attained-age-rated policies increase premiums as you get older. While community- and issue-age-rated policies typically cost more initially, they may prove less expensive long-term than attained-age policies that increase substantially as you age.

Look for household discounts, non-smoker discounts, and discounts for paying annually instead of monthly. Some companies offer discounts of 5-15% for couples buying policies together. Ask about all available discounts when comparing premiums.

Consider the company's financial stability and customer service reputation. Check A.M. Best ratings for financial strength and read customer reviews. While price matters, reliable claims payment and good customer service prove equally important when you need care.

Medigap provides valuable financial protection and peace of mind for Original Medicare beneficiaries. By understanding plan options, comparing premiums, and enrolling at the right time, you can secure comprehensive coverage that protects against unexpected healthcare costs throughout retirement.