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Mainstreet Financial Education · Medicare Supplement

Medigap basics, filling the gaps in Medicare.

Original Medicare does not cover everything. A Medigap policy is standardized private insurance designed to pick up much of what is left. Here is how it works.

How Medigap works

Medigap is private insurance that helps pay the out-of-pocket costs Original Medicare leaves behind, such as coinsurance, copays, and deductibles. Plans are standardized and sold by letter (A, B, D, G, K, L, M, N, and others), so a Plan G from one insurer covers the same benefits as a Plan G from another. The difference between insurers is price and service, not coverage. Massachusetts, Minnesota, and Wisconsin run their own standardized systems.

What Medigap can help cover

BenefitWhat it helps with
Part A coinsuranceHospital copays for days 61–150, plus up to 365 additional lifetime days paid in full
Part B coinsuranceThe share you owe for doctor visits, labs, and outpatient services
Part A deductibleThe $1,736 inpatient hospital deductible per benefit period (2026)
Skilled nursing coinsuranceThe $217 per day cost for days 21–100 (2026)
Foreign travel emergencyA portion of emergency care abroad, up to plan limits
First three pints of bloodThe cost Original Medicare does not cover

Plans C and F

  • Available only if you became eligible for Medicare before January 1, 2020
  • Plans F and G also offer a high-deductible option, $2,950 in 2026 before coverage starts

Plans K and L

  • Pay a share of Part A and B copays until you hit an annual out-of-pocket maximum
  • In 2026, that maximum is $8,000 for Plan K and $4,000 for Plan L, then they pay 100%

The window that matters

Buy when you are guaranteed acceptance. Your strongest guaranteed-issue window is the six months that begin when you are 65 and enrolled in Part B. Inside it, an insurer cannot turn you down or charge more for your health. After it closes, most states let insurers underwrite, so timing is part of the decision.

Teaching, never a sales pitch

Timing is part of the decision.

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