8.3 Medigap (Medicare Supplement Insurance)

Medicare Supplement Insurance (Medigap) Overview

Medigap (Medicare Supplement Insurance) is private insurance sold to people with Original Medicare (Part A and Part B) to help pay the cost sharing — deductibles, coinsurance, and copayments — that Original Medicare does not cover. Medigap policies are standardized by federal law so that plans with the same letter offer identical benefits regardless of the insurer selling them.

Quick Answer: Medigap Plans A–N are standardized; Plans C and F are no longer sold to people first eligible for Medicare after January 1, 2020 (Plan G is the most popular replacement). Medigap covers Original Medicare cost sharing, cannot be combined with Medicare Advantage, and is bought during a 6-month open enrollment window starting with Part B.

Standardized Plans (Modernized 2010)

The modernized set of plans became effective June 1, 2010. Ten standardized plans are sold in most states (Massachusetts, Minnesota, and Wisconsin standardize differently):

Plans C and F: Closing to New Eligibles

Because Plans C and F cover the Part B deductible, and the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA) prohibited the sale of plans that cover that deductible to people first eligible for Medicare on or after January 1, 2020, Plans C and F are no longer available to new-eligibles. People who were eligible before that date may keep their policy or buy another if they have guaranteed issue rights. Plan G — identical to F except for the Part B deductible — became the most popular choice among new-eligibles.

Core (Basic) Benefits

All Medigap plans include the core (Plan A) benefits:

• Part A coinsurance and hospital costs up to an additional 365 days after Medicare benefits are exhausted.
• Part B coinsurance or copayment.
• Blood (first 3 pints).
• Part A hospice care coinsurance or copayment.

Additional benefits layered on top include: the Part A deductible, the Part B deductible (legacy plans only), skilled nursing facility (SNF) coinsurance, Part B excess charges (Plans F and G only), foreign travel emergency, and at-home recovery.

High-Deductible Plan F

A high-deductible Plan F version was available; its deductible is indexed annually. Plans sold as high-deductible require the beneficiary to meet the deductible before the plan pays any benefit. High-deductible F was also closed to new-eligibles on January 1, 2020, but existing policies may be renewed.

Enrollment and Guaranteed Issue

Open enrollment lasts six months, beginning the first month a person is 65 or older and enrolled in Part B. During this window, an insurer cannot deny coverage or charge more for pre-existing conditions. After open enrollment, Medigap is generally medically underwritten except in states with community rating or at guaranteed issue trigger events.

Guaranteed issue rights arise when the beneficiary loses coverage through no fault of their own — for example, employer coverage ending, an MA plan leaving the area, or moving out of a plan's service area. In these situations, the insurer must issue a policy without medical underwriting.

Medigap Cannot Combine with MA

A beneficiary cannot have a Medigap policy and a Medicare Advantage plan at the same time. Selling a Medigap policy to an MA enrollee is prohibited, and an MA enrollee who wants Medigap must disenroll from MA first. Medigap supplements only Original Medicare.

What Medigap Does NOT Cover

Medigap is a supplement to Original Medicare only. It does not cover:

• Standalone prescription drugs (that is Part D).
• Long-term care (custodial care).
• Vision, dental, or hearing aids.
• Private nursing.

Foreign Travel Emergency Coverage

Several Medigap plans (C, D, F, G, M, and N) include foreign travel emergency coverage for care received outside the United States. This benefit typically pays 80% of the cost of emergency care that begins during the first 60 days of a trip, after a small annual deductible, subject to a lifetime maximum. It is meant for emergencies only — routine care abroad is not covered, and it does not replace travel insurance. For new-eligibles, Plan G is the most popular way to obtain this benefit because Plans C and F are closed.

Key Exam Pointers

• Plans with the same letter offer the same benefits regardless of insurer (federal standardization).
• Plans C and F are closed to new-eligibles after January 1, 2020.
• Plan G is the most popular among new-eligibles.
• The 6-month open enrollment begins with Part B; guaranteed issue rights apply on qualifying events.
• Medigap cannot be combined with Medicare Advantage.