Educational content only. Not Medicare, insurance, or financial advice. Not affiliated with CMS, Medicare.gov, or SSA.
By Keith Guirao, founder and editor of Savvy Senior Central (Maven Media).
The decision is not “which brand is best.” It is which extra-coverage path you want after you already have Part A and Part B, and whether you are willing to leave a one-time underwriting window behind.
Medicare Supplement Insurance (Medigap) is private insurance that helps pay your share of Original Medicare cost sharing, certain deductibles, coinsurance, and copays, depending on the lettered plan. Medicare Advantage (Part C) is a Medicare-approved private plan that delivers Part A and Part B (and usually Part D) a different way. When you are getting started, you can buy Medigap or enroll in Advantage. You cannot have both as usable coverage at the same time.
You cannot use Medigap to pay Advantage copays, deductibles, coinsurance, or premiums. Selling Medigap to someone enrolled in Advantage is illegal unless they are switching back to Original Medicare (or Advantage coverage will end before the Medigap policy starts). That is Medicare.gov’s stacking rule, not a sales objection.
I have spent 18 years inside consumer marketing and lead generation in insurance and health, building the campaigns and forms that push people toward these products. That is operator experience, not a counseling credential. The mail treats Medigap and Advantage as mix-and-match extras. They are two different paths.
Path A vs Path B: what you are actually choosing
Path A. Original Medicare + Medigap (+ usually a separate Part D.) You use any doctor or hospital that takes Medicare. After Medicare pays its share, Medigap pays according to the letter you bought. You keep paying the Part B premium. In 2026 most people pay the standard Part B premium of $202.90. Medigap premiums are separate, private, and vary by company, letter, age, and ZIP. There is no national Medigap premium on CMS’s fact sheet, so this page does not invent one. Medigap sold after 2005 does not include drugs.
Path B. Medicare Advantage. You still pay Part B. You get most A and B services through the plan card. Most plans bundle Part D. Plans must set a yearly limit on what you pay for covered Medicare services. In exchange you often accept networks, referrals, and prior authorization. Extras such as dental, vision, and hearing are plan-specific marketing language. CMS’s words are “may” and “most plans,” not a federal guarantee.
| Axis | Original + Medigap | Medicare Advantage |
|---|---|---|
| Provider access | Any that take Medicare (nationwide) | Often network / service-area rules for non-emergency care |
| Cost shape | Medigap fills lettered shares of Original cost sharing | Plan copays + yearly medical OOP limit (amount varies by plan) |
| Drugs | Separate Part D usually | Usually bundled; HMO/PPO without drugs is a trap (see Part D guide) |
| Stacking | Medigap pairs only with Original | Medigap cannot pay Advantage costs |
| Timing risk | One-time federal Medigap open enrollment at 65/Part B | Fall AEP / Jan-Mar OEP move plans; Medigap later may be underwritten |
You pick a path. You do not stack them.
The stacking rule, in Medicare.gov’s words
- You can buy Medigap or enroll in Advantage, but you cannot have both as usable coverage.
- You cannot buy Medigap while you are in Advantage unless you are switching back to Original Medicare.
- You cannot use Medigap to pay Advantage cost sharing or premiums.
- It is illegal to sell you Medigap if they know you are in Advantage, unless you are switching back (or Advantage ends before Medigap starts).
- It is illegal to claim a Medigap policy is part of the Medicare program, or to claim an Advantage plan is a Medigap policy.
If you keep a Medigap policy after you join Advantage, you will be paying for coverage you cannot use. Contact the Medigap company if you intend to drop it. In most cases, if you drop Medigap to join Advantage, you may not get the same policy back unless you leave during a trial period Medicare.gov describes.
What Medigap is and what standardization means
Medicare.gov: Medigap is extra insurance from a private company to help pay your share of out-of-pocket costs in Original Medicare. You generally must have Part A and Part B first. One policy covers one person. Spouses each buy their own.
In most states, policies are standardized by letter: A, B, C, D, F, G, K, L, M, and N. Policies with the same letter offer the same basic benefits no matter which company sells that letter. Price is the variable. This page does not rank letters and does not name carriers.
Once you buy a standardized policy, it renews automatically every year even if you have health problems. The company can drop you only in narrow cases Medicare.gov lists (stop paying premiums, material misrepresentation on the application, or the company goes bankrupt or out of business).
Massachusetts, Minnesota, and Wisconsin standardize Medigap differently. Some states offer Medicare SELECT (network hospitals, and sometimes doctors, for full benefits). State law can add rights. Confirm with Medicare.gov, your State Insurance Department, or SHIP.
The 2026 Medicare.gov benefit chart (reference, not a ranking)
This table follows Medicare.gov’s compare-plan-benefits page. A “Yes” means the plan covers 100% of that benefit. A percentage means the plan covers that share and you pay the rest. A dash means the plan does not cover it. Not every letter is sold in every state; all companies that sell Medigap must offer at least Plan A.
| Benefit | A | B | C | D | F* | G* | K | L | M | N |
|---|---|---|---|---|---|---|---|---|---|---|
| Part A coinsurance / hospital costs up to an extra 365 days after Medicare benefits used | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Part B coinsurance or copayment | Yes | Yes | Yes | Yes | Yes | Yes | 50% | 75% | Yes | Yes*** |
| Blood (first 3 pints) | Yes | Yes | Yes | Yes | Yes | Yes | 50% | 75% | Yes | Yes |
| Part A hospice coinsurance or copayment | Yes | Yes | Yes | Yes | Yes | Yes | 50% | 75% | Yes | Yes |
| Skilled nursing facility coinsurance | . | . | Yes | Yes | Yes | Yes | 50% | 75% | Yes | Yes |
| Part A deductible | . | Yes | Yes | Yes | Yes | Yes | 50% | 75% | 50% | Yes |
| Part B deductible | . | . | Yes | . | Yes | . | . | . | . | . |
| Part B excess charge | . | . | . | . | Yes | Yes | . | . | . | . |
| Foreign travel emergency (up to plan limits) | . | . | 80% | 80% | 80% | 80% | . | . | 80% | 80% |
| Out-of-pocket limit in 2026 | n/a | n/a | n/a | n/a | n/a | n/a | $8,000 | $4,000 | n/a | n/a |
\* Plans F and G also offer a high-deductible option in some states. You pay Medicare-covered costs (coinsurance, copayments, and deductibles) up to $2,950 in 2026 before the policy pays anything.
\*\* For Plans K and L, after you meet the out-of-pocket yearly limit and the yearly Part B deductible ($283 in 2026), the Medigap plan pays 100% of covered services for the rest of the calendar year. Prefer the live Medicare.gov chart over older booklet footnotes that accidentally print the Part B *premium* where the deductible belongs.
\*\*\* Plan N pays 100% of Part B service costs except copayments for some office visits (up to $20) and some ER visits that do not result in inpatient admission (up to $50), as the official booklet states.
The Medigap clock is one time. It is not AEP
Under federal law you get a six-month Medigap Open Enrollment Period. It starts the first month you have Part B and you are 65 or older. During that window, in most situations, the company cannot refuse to sell you any Medigap policy it offers because of pre-existing health problems, and cannot charge more because of those problems. It can still impose a pre-existing-condition waiting period of up to six months for conditions treated or diagnosed in the six months before the policy starts, unless you have enough creditable coverage to shorten or eliminate it. Original Medicare still covers the Medicare-covered service during that wait; you pay the Medicare coinsurance or copayment.
This window does not repeat every fall. It is not the October 15-December 7 Medicare Open Enrollment Period (AEP). If you miss it, there is no federal guarantee a company will sell you a policy. It may cost more. The company may medically underwrite and may deny you unless a guaranteed-issue right applies.
Common federal guaranteed-issue triggers include losing certain other coverage, an Advantage plan leaving Medicare or its service area, or using a trial right. You generally apply no more than 63 days after the coverage ends, and you may need the notices as proof. Some states add rights, including for people under 65. Federal law generally does not require companies to sell Medigap to people under 65.
If you have group coverage from current work, you may want to wait to sign up for Part B. Your one-time Medigap Open Enrollment starts when you sign up for Part B (even if you still have employer coverage), and it cannot be repeated. When that employer coverage ends you can often sign up for Part B without a late penalty, and the Medigap window starts then. See Medicare and working past 65 and the enrollment windows guide.
Plans C and F are closed to people newly eligible after January 1, 2020
If you first became eligible for Medicare on or after January 1, 2020, you generally cannot buy Plan C or Plan F (including high-deductible F in most cases). Those letters still exist for people who were already eligible before that date. Plan G is the letter that most closely matches what Plan F used to do for newly eligible people, except Plan G does not cover the Part B deductible. Confirm current availability for your ZIP on Medicare.gov; this page does not sell policies.
Trial rights: a way back, not a stack
A first-time move into Advantage can trigger a 12-month trial right to return to Original Medicare and buy Medigap in situations Medicare.gov describes. If you dropped a Medigap policy to join Advantage for the first time, you may have a single 12-month period to get that policy back if the same company still sells it. If it is not available, certain letters may be available depending on state law and whether you were new to Medicare on or after January 1, 2020. If you joined Advantage when you were first eligible for Part A at 65, you may buy certain policies sold in your state if you switch to Original Medicare within the first year.
Those trial rights are a path back. They do not make Medigap and Advantage stackable while you stay in Advantage.
What Medigap generally does not cover
Medicare.gov lists items Medigap generally does not cover: long-term care (help with bathing, dressing, using the bathroom), vision or dental care, hearing aids, eyeglasses, or private-duty nursing. Foreign-travel emergency coverage on certain letters is a Medigap extra with plan limits, not a Medicare international benefit. Original Medicare generally does not cover care outside the United States.
If you need drug coverage with Path A, buy a separate Part D plan. The 2026 Part D yearly out-of-pocket cap for covered Part D drugs is $2,100; the national base beneficiary premium used for late-enrollment penalty math is $38.99. Neither figure is a Medigap premium.
2026 federal costs that sit under either path
CMS published these on November 14, 2025:
- Part B standard premium: $202.90/month (most people; IRMAA may add more (see SSA’s IRMAA pages).
- Part B deductible: $283/year.
- Part A inpatient deductible per benefit period: $1,736; days 61-90 $434/day; lifetime reserve days $868/day; SNF days 21-100 $217/day.
- About 99% of beneficiaries pay $0 Part A premium (40+ quarters); buy-in rates $311 / $565 if you must purchase Part A.
Advantage plans set their own copays for many of those same stays. Medigap letters decide which Original shares the supplement pays. Compare live documents (Evidence of Coverage for Advantage, the lettered outline for Medigap), not last year’s brochure.
A practical sequence (not advice)
- Doctors and hospitals you will not leave. Nationwide Original + Medigap usually wins on access; Advantage wins only if your providers sit inside a viable network for your ZIP.
- Medigap clock. If Path A is the destination, treat the six-month window at 65/Part B as a closing door AEP does not reopen.
- Drug list. Enter prescriptions in Medicare Plan Compare whether you want a PDP or an Advantage plan with drugs.
- Travel / dual homes. County HMOs and dual residences are a poor match more often than ads admit.
- Confirm. Medicare.gov, 1-800-MEDICARE, or SHIP, not a ranked carrier list.
This page does not rank carriers, name “best” Medigap letters or Advantage plans, or treat a marketplace quote as a CMS figure.
FAQ
Can I have Medigap and Medicare Advantage at the same time?
No. You choose Medigap *or* Advantage, not both as usable coverage. Medigap cannot pay Advantage copays, deductibles, coinsurance, or premiums.
When is the Medigap Open Enrollment Period?
Generally six months beginning the first month you are 65 and enrolled in Part B. It is not the fall Medicare Open Enrollment Period. Missing it can mean medical underwriting later unless a guaranteed-issue right or more generous state rule applies.
Why can’t newly eligible people buy Plan C or Plan F?
If you first became eligible for Medicare on or after January 1, 2020, federal rules generally close Plans C and F to you. People eligible before that date may still buy them where offered.
Does Medigap cover dental, vision, hearing aids, or long-term care?
Generally no. Those sit outside standardized Medigap benefits. Some Advantage plans *may* offer dental/vision/hearing extras; those are plan-specific, not Part A/B.
Does Medigap cover emergency care abroad?
Some letters (C, D, F, G, M, N) include foreign-travel emergency coverage up to plan limits after a deductible. Original Medicare generally does not cover foreign care. Confirm the outline of coverage.
Do I still pay the Part B premium if I buy Medigap?
Yes. You keep Part A and Part B, keep paying Part B ($202.90 standard in 2026 for most people), and pay the Medigap premium to the private company.
If I join Advantage for a year, can I always buy Medigap later with no health questions?
Not always. Outside the one-time federal open enrollment (and outside guaranteed-issue or trial-right situations), insurers in most states may underwrite and may decline. Do not assume AEP recreates the Medigap window.
Is a $0 Advantage premium the same as free coverage?
No. You still owe Part B (and any IRMAA). Plan copays and the plan’s medical out-of-pocket maximum still apply. The $0 refers to the plan premium, which can change each year.
Sources
Every figure above traces to CMS or Medicare.gov. We do not cite insurance marketplaces for data. Figures last verified September 22, 2026 (ET).
- Medicare.gov: What's Medicare Supplement Insurance (Medigap)?
- Medicare.gov: Compare Medigap plan benefits
- Medicare.gov: How Medigap works
- Medicare.gov: Compare Original Medicare & Medicare Advantage
- CMS: 2026 Medicare Parts A & B Premiums and Deductibles (Nov. 14, 2025)
- Medicare.gov: 2026 Medicare Costs (Publication 11579)
- Medicare.gov: Medicare & You 2026 (Publication 10050)
- Medicare.gov: Choosing a Medigap Policy (Publication 02110)
- Medicare.gov: Avoid late enrollment penalties (Part D base $38.99; Part B example uses $202.90)
