Do You Really Need Medicare Supplement Insurance?

Original Medicare leaves two large gaps in coverage: a $1,736 Part A deductible in 2026 and 20% co-insurance on Part B services with no annual cap. Medicare Supplement insurance, also called Medigap, is private health insurance that pays costs Original Medicare doesn't cover. Medicare pays its share first, then your Medigap plan covers the remainder up to its benefit limits. 

Plan benefits are standardized by the federal government. A Plan G from one insurer covers the same benefits as a Plan G from any other insurer. Premiums differ, but benefits don't. Medigap requires enrollment in Original Medicare Parts A and B and can't be paired with Medicare Advantage. The gap it fills is specific to Original Medicare's cost-sharing structure.

People who use medical care frequently or live on fixed incomes benefit most from Medigap. The 20% Part B co-insurance has no cap. A beneficiary with $100,000 in covered outpatient costs in a year owes $20,000 out of pocket. Plan G premiums average $150 to $250 per month depending on age and state, but that fixed monthly cost replaces unpredictable bills at the point of care.

Frequent travelers and people who see specialists across state lines also benefit from Medigap's any-provider, any-hospital access, with no network restrictions. Medicare Advantage locks enrollees into a plan network and often requires prior authorization for specialist visits.

The best time to buy Medigap is during your Medigap Open Enrollment Period, the six-month window that starts the month you turn 65 and are enrolled in Part B. During this window, insurers can't deny coverage or charge higher premiums based on health status. Missing this window means medical underwriting applies in most states, and a pre-existing condition can result in higher premiums or denial.

Skipping Medigap makes sense in two cases: 

1. You're enrolling in Medicare Advantage, which covers similar cost gaps through network-based plans.
2. You're in excellent health with low expected utilization and can absorb the cost-sharing risk

Compare best Medicare Advantage plans if you're considering the Medicare Advantage path.

Medicare Supplement premiums vary by plan, age, and insurer, but most people pay between $110 and $300 per month. Premiums increase with age, and plans with broader coverage, like Plan G or F, cost more than lower-coverage options like Plan K or N:

Medicare offers 10 standardized Medigap plans, labeled A, B, C, D, F, G, K, L, M and N. Each covers a different mix of out-of-pocket costs, and the letters reflect benefits, not quality.

The most popular plans are Plans G, F and N. Plan G covers everything Plan F does except the Part B deductible. Plan N covers the Part A deductible and Part B coinsurance but includes copays of up to $20 for office visits and $50 for ER visits, and it does not cover Part B excess charges. Plan G and Plan N differ on three points: excess charges, copays and premiums. Plan G covers excess charges and has no visit copays, but costs more. Plan N has lower premiums of $30 to $50 less per month, but requires some cost-sharing.

Plan G is best if you want predictable costs and minimal billing surprises, while Plan N is better for healthy enrollees comfortable with small copays in exchange for lower premiums.

Medigap and Medicare Advantage are mutually exclusive. You can't have both policy types at the same time. Medigap pairs with Original Medicare and carries no network restrictions, so you can see any provider who accepts Medicare anywhere in the country. Medicare Advantage restricts enrollees to a plan network and often requires prior authorization for specialist care and procedures.

Many Medicare Advantage plans carry a $0 monthly premium beyond Part B, while Medigap plans charge an additional premium on top of Part B. Medigap's premium buys predictability, with near-zero out-of-pocket costs at the point of care. Medicare Advantage's $0 premium comes with cost-sharing at each visit and a plan-set annual maximum out-of-pocket limit. Dental and vision coverage is available only through Medicare Advantage; Medigap does not include these benefits.

Frequent travelers, people with out-of-network specialists, or anyone who wants no-surprise billing are better fits for Medigap. People who want extra benefits like dental, vision and hearing, are healthy and low-utilization, or are comfortable with a network are better fits for Medicare Advantage.