Medigap: Medicare Supplement Insurance Explained (2026)

What Medigap is and isn't

Medigap is supplemental insurance sold by private insurance companies. It pairs with Original Medicare (Parts A and B), not with Medicare Advantage. Key features:

• Federally standardized — Plan G in Ohio covers the same things as Plan G in any other state. Carriers can vary only in premium and customer service, not in benefits.
• Identified by letter (A, B, C, D, F, G, K, L, M, N) — these are the active plan letters. (Earlier letters like H, I, J were retired.)
• Sold by private insurers — Aetna, Anthem BCBS, Humana, UnitedHealthcare/AARP, Mutual of Omaha, Cigna, and many others sell Medigap policies in Ohio. The same plan letter from different carriers covers identical benefits.
• Premium-only product — you pay a monthly Medigap premium and minimal or no cost-sharing for covered services. There's no separate deductible or coinsurance beyond what's specified in the plan letter.

Medigap is NOT:

• The same as Medicare Advantage — Medigap supplements Original Medicare; MA replaces it.
• Prescription drug coverage — Medigap doesn't include Part D. You buy a separate Part D plan if you want drug coverage.
• Vision, dental, or hearing coverage — Medigap covers Original Medicare cost-sharing only; these benefits require separate insurance or out-of-pocket payment.

The 10 standardized plan letters

*Plans C and F: Closed to people newly Medicare-eligible after January 1, 2020.
†Plan N: Includes a $20 copay for some office visits and $50 copay for ER visits not resulting in admission.

"100%" in the table means the plan covers that cost-sharing in full. "—" means the plan doesn't cover that item; you pay it. "50%" and "75%" indicate Plans K and L's partial cost-sharing structure with their MOOPs ($8,000 and $4,000 respectively in 2026).

Plan G: the most popular choice today

Plan G is the most-purchased Medigap plan for people newly Medicare-eligible after January 1, 2020. It covers:

• Part A coinsurance and hospital costs for the duration of stay (and 365 days after Medicare benefits run out).
• Part A deductible ($1,736 in 2026).
• Part B coinsurance (the 20% Medicare doesn't cover).
• Part B excess charges (if any doctor accepts assignment but bills above Medicare's approved amount — rare in most cases).
• Foreign travel emergency (80%, up to plan limits).
• Skilled nursing facility coinsurance ($217/day for days 21-100 in 2026).
• First 3 pints of blood (rare modern need).
• Hospice care coinsurance.

What Plan G doesn't cover: the annual Part B deductible ($283 in 2026). You pay that out-of-pocket before Plan G coverage kicks in for Part B services. After the deductible, Plan G covers essentially everything.

For most Medicare beneficiaries, Plan G produces highly predictable annual costs: monthly premium + $283 Part B deductible + nothing else for medical services. This predictability is a major reason for Plan G's popularity.

Plan N: the lower-premium alternative

Plan N is identical to Plan G except for three things:

1. Office visit copay: $20 per visit for in-office doctor visits.
2. ER copay: $50 per ER visit (waived if you're admitted to the hospital).
3. Plan N doesn't cover Part B excess charges.

In exchange for these modest cost-sharing items, Plan N typically has premiums 20-30% lower than Plan G. For healthy retirees with infrequent doctor visits, Plan N can cost less overall than Plan G — the premium savings exceed the occasional copays.

For retirees with frequent specialist visits or chronic conditions requiring frequent appointments, the copays can add up — Plan G's higher premium but $0 cost-sharing produces more predictable budgeting.

Why Plans C and F are closed to newer beneficiaries

The MACRA (Medicare Access and CHIP Reauthorization Act) of 2015 closed Plans C and F to anyone newly Medicare-eligible after January 1, 2020. The reason: C and F covered the Part B deductible (then $185, now $283 in 2026), and Congress believed eliminating first-dollar coverage would encourage more cost-conscious Medicare utilization.

• If you were Medicare-eligible before January 1, 2020: you can still enroll in or keep Plans C or F. These plans are open to "grandfathered" beneficiaries.
• If you became Medicare-eligible after January 1, 2020: Plans C and F aren't available to you. Plan G is the closest equivalent (covers everything except the Part B deductible).

Practical effect for newly-eligible Ohio retirees: Plan G is the de facto top-tier choice. For most, Plan G + Original Medicare produces the most comprehensive coverage with predictable costs.

Plans K and L: cost-sharing alternatives

Plans K and L are the "high-deductible" alternatives among Medigap plans — they cover less cost-sharing but have lower premiums and explicit MOOP caps:

• Plan K: covers 50% of most cost-sharing items. Has an $8,000 annual MOOP (2026); after MOOP, pays 100% for the rest of the year.
• Plan L: covers 75% of most cost-sharing items. Has a $4,000 annual MOOP (2026); after MOOP, pays 100%.

K and L premiums are lower than G or N but you pay more out-of-pocket for routine care. For healthy retirees comfortable with somewhat higher cost-sharing in exchange for lower premium, K and L can work. For most, G or N are simpler.

Medigap Open Enrollment Period in Ohio

Your Medigap Open Enrollment Period is your one federally-guaranteed window for buying Medigap without medical underwriting:

• When it starts: the first day of the month you're both 65 or older AND enrolled in Part B.
• How long it lasts: 6 months.
• What it guarantees: any Medigap policy offered to people in your state must be sold to you without health questions or pre-existing condition exclusions during this period.

Ohio doesn't have a "birthday rule" — unlike California, Oregon, Nevada, Washington, Idaho, Illinois, Louisiana, Maryland, Kentucky, Missouri, and Oklahoma (which all have some form of annual or birthday-period guaranteed-issue Medigap rule). After your initial 6-month OEP in Ohio, changing Medigap plans typically requires medical underwriting — carriers can deny you for pre-existing conditions.

Practical consequence: choose your Medigap plan carefully during your initial 6-month OEP. Switching later is possible but conditional on health. The under-65 disabled in Ohio have their own guaranteed-issue windows — see our Medigap in Ohio page for those rules.