Medigap Plans: What They Cover and How to Choose
Medigap plans are private health insurance policies designed to cover out-of-pocket costs left by Original Medicare, including deductibles, coinsurance, and copayments. They do not replace Medicare but work alongside it. Because the federal government standardizes these plans by letter, the core benefits of Plan G, for example, are the same no matter which insurer sells it. This structure makes comparison straightforward, but costs, availability, and extras vary by state and carrier.
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How Medigap Works with Original Medicare
When you have Original Medicare, Part A and Part B cover a share of approved costs, leaving you responsible for the rest. Medigap picks up some or all of those remaining amounts, depending on the plan letter. The policies are sold by private companies, and each plan must follow federal and state rules to be labeled by letter. If you have a Plan G from one insurer, its basic coverage matches a Plan G from another, though the premium and service details can differ.
What Medigap Plans Typically Cover
Coverage depends on the plan letter, but most standardized Medigap policies help with:
- Medicare Part A hospital coinsurance and copayments, including an extra 365 days of hospital coverage after Medicare benefits run out.
- Medicare Part B coinsurance or copayment for doctor and outpatient services.
- Blood transfusions beyond the first three pints covered by Medicare.
- Skilled nursing facility coinsurance.
- Medicare Part A and Part B deductibles, on plans that include this benefit.
- Emergency medical care when you travel outside the United States, up to plan limits.
Medigap does not cover long-term care, vision, dental, hearing aids, eyeglasses, or private-duty nursing. It also does not cover services Medicare does not approve, though some plans may cover certain excess charges from providers who accept assignment.
Standard Plan Letters and Key Differences
The ten standardized plan letters available in most states are A, B, C, D, F, G, K, L, M, and N. Availability varies, and some letters are being phased out for new enrollees. High-deductible versions of Plan F and Plan G also exist. Below is a compact comparison of what drives the main differences.
| Factor | Detail | Context |
|---|---|---|
| Core benefits | Identical within each letter | Federal standardization ensures the same base coverage across insurers. |
| Premiums | Vary by company, location, age, and underwriting | Two people on the same plan can pay very different rates. |
| Part B excess charges | Coverable on some plans, not others | Plan G and Plan N do not cover excess charges by default. |
| High-deductible option | Available on Plan F and Plan G | You pay a larger deductible before the plan pays anything. |
Costs and Premium Structures
Medigap premiums are priced in one of three ways. Community-rated pricing charges the same premium regardless of age. Issue-age-rated pricing bases your premium on how old you are when you buy the policy, so younger buyers often pay less. Attained-age-rated pricing adjusts the premium as you age, meaning it can rise over time. Beyond the premium, consider out-of-pocket costs such as deductibles, copayments, and the Part B excess charge coverage when comparing plans.
When You Can Enroll and What to Watch For
The best time to buy a Medigap policy is during the six-month Medigap open enrollment period, which starts on the first day of the month you turn 65 and are enrolled in Medicare Part B. During this window, insurers must sell you any plan they offer and cannot use medical underwriting, even if you have health problems. Outside that period, companies may deny coverage or charge higher premiums based on your health history. Some states also offer additional guaranteed-issue rights, such as when you lose employer coverage.
Choosing the Right Medigap Plan
Start by confirming you have Original Medicare, because Medigap does not work with Medicare Advantage. Then compare standardized benefits across the same plan letter to see which carrier offers the best premium and service. Check whether the plan covers Part B excess charges, since that can affect your total out-of-pocket cost. Finally, review the insurer's claims process, customer service reputation, and whether your doctors accept assignment, since Medigap only pays its share after Medicare approves the claim.
Medigap and Other Coverage
You cannot hold both a Medigap policy and a Medicare Advantage plan at the same time. If you switch from Original Medicare plus Medigap to a Medicare Advantage plan, you can drop the Medigap, but getting a new Medigap policy later may require medical underwriting. Similarly, if you have employer or retiree coverage, check whether that insurance works alongside or instead of Medigap, as coordination of benefits rules can change what each payer covers.