Medigap Plans (Medicare Supplement Plans): How They Work, What They Cover, and When to Enroll

Medigap plans—also called Medicare Supplement plans—work with Original Medicare (Parts A & B) to help pay your out-of-pocket costs. They don’t replace Medicare. They fill gaps like deductibles, coinsurance, and copays so your costs are more predictable.

At Medigap Sherpas, we compare carriers, simplify choices, and help you enroll—no pressure, no jargon.

What Is a Medigap (Medicare Supplement) Plan?

• Private insurance that supplements Original Medicare.
• Standardized plan letters (A, B, D, G, K, L, M, N).
• Use any doctor or hospital that accepts Medicare—no networks.
• Not the same as Medicare Advantage (Part C).

You must have Part A and Part B to buy a Medigap plan, and you’ll keep Original Medicare as your primary coverage.

What Medigap Typically Covers

Medigap helps pay the Medicare cost-sharing you’d otherwise owe:

• Part A coinsurance and hospital costs (extra 365 days after Medicare benefits end)
• Part B coinsurance/copays (often 20%)
• Blood (first 3 pints)
• Part A hospice coinsurance/copays
• Skilled nursing facility coinsurance (varies by plan letter)
• Part A deductible (varies by plan letter)
• Part B excess charges (Plans F and G)
• Foreign travel emergency (Plans C, D, F, G, M, N; limits apply)

What Medigap Doesn’t Cover

• Prescription drugs (add a Part D plan)
• Routine dental, vision, or hearing services
• Long-term care, private-duty nursing, most custodial care

Popular Plan Choices (High-Level)

• Plan G: Broad coverage; does not cover the Part B deductible; includes Part B excess charges and foreign travel emergency.
• Plan N: Lower premium; small copays for some visits; doesn’t cover Part B excess charges.
• Plan F/C: Only available if you were first eligible for Medicare before Jan 1, 2020.
• Plans K and L have lower premiums with cost-sharing and annual out-of-pocket limits.

Who’s Eligible?

You’re typically eligible if:

• You have Medicare Part A and Part B
• You live in a state where the plan is offered
• You’re 65+ (some states offer Medigap to beneficiaries under 65 on Medicare due to disability)
• You cannot use Medigap with a Medicare Advantage plan.

When to Enroll (and Why Timing Matters)

• Medigap Open Enrollment Period (OEP):
  A 6-month window that starts the first day of the month you’re both 65 or older and enrolled in Part B. During OEP, you can buy any Medigap plan sold in your state—no medical underwriting.
• Guaranteed-Issue Rights (GI):
  Special situations (like losing certain coverage) may let you buy specific Medigap plans without underwriting.
• Outside OEP/GI:
  You may need to answer health questions, and a carrier can accept or decline based on underwriting.

Medigap vs. Medicare Advantage (Quick Comparison)

• Original Medicare + Medigap (+ Part D):
  Nationwide access to Medicare-accepting providers, no networks, predictable costs.
• Medicare Advantage (Part C):
  Private plan alternative with networks and plan rules; often bundles drugs and extras.

Your choice depends on flexibility, budget, medications, and travel needs.