Medicare Supplement Plans

Original Medicare covers a large share of your medical costs, but not all of it. Medicare Supplement insurance — usually called Medigap — is built to pay the piece that's left over: deductibles, coinsurance, and copays. Here's how these plans actually work, how they're standardized, and what's worth understanding before you buy one.

What a Medicare Supplement Plan Actually Does

Original Medicare Part B typically pays 80% of the Medicare-approved cost for outpatient care, leaving you responsible for the remaining 20% with no cap on that exposure. A Medicare Supplement policy is designed to pick up some or all of that remaining share, along with hospital deductibles and other cost-sharing Original Medicare passes on to you. Medicare pays its portion of a claim first; your Medigap policy then pays its portion, based on which plan you have.

A few things distinguish how Medigap works compared to other Medicare coverage paths:

  • You can use it with any doctor or hospital in the country that accepts Medicare — there's no provider network to stay inside of.
  • Coverage is guaranteed renewable, meaning the insurer can't cancel your policy or raise your rate specifically because of your health, as long as you keep paying premiums.
  • Each policy covers one person. If your spouse also has Medicare, they'll need their own separate policy (though some insurers offer a household discount).
  • There's no annual lock-in the way there is with Medicare Advantage — you're free to drop a Medigap policy at any time.
  • You must already be enrolled in Medicare Part A and Part B to buy one.
Worth knowing: Medigap plans don't include Part D prescription drug coverage, and they don't cover routine dental, vision, or hearing care — since Original Medicare doesn't cover those either, there's nothing for a supplement plan to "supplement" there. Most people pair a Medigap policy with a separate, standalone Part D plan.

The Standardized Plans, Explained

Since 1990, federal law has required Medigap policies to follow a standardized structure. Each plan is assigned a letter, and — outside of Massachusetts, Minnesota, and Wisconsin, which use their own state-specific standardization — a plan with a given letter must offer identical benefits no matter which insurance company sells it. A Plan G from one company covers exactly the same things as a Plan G from any other company. The only meaningful difference between companies is the premium they charge.

Ten standardized plans currently exist: A, B, D, G, K, L, M, and N, plus Plan G and Plan F in high-deductible versions. Plans C and F are closed to anyone who became newly eligible for Medicare on or after January 1, 2020 — if you were already eligible before that date, you can keep an existing Plan C or F, or still enroll in one for the first time. Plans E, H, I, and J are no longer sold to anyone.

A Closer Look at a Few Common Plans

Rather than list all ten, here's what three of the more frequently discussed options actually cover:

Plan G

Covers all standard Medicare cost-sharing except the annual Part B deductible, which you pay out of pocket first ($283 in 2026).

Open to anyone with Medicare, regardless of when you became eligible.

Plan N

Covers most of the same gaps as Plan G, but with small copays — typically up to $20 for some office visits and up to $50 for ER visits that don't lead to admission.

Usually carries a lower premium in exchange for that cost-sharing.

High-Deductible Plan G

Works like Plan G once you've paid a yearly deductible out of pocket first ($2,950 in 2026); after that, it covers the same gaps at 100%.

Lower monthly premium, higher upfront responsibility if you need care.

Note: these dollar figures are set annually and change most years — the numbers above reflect 2026 amounts.

The Full Comparison Chart: All Ten Plans

Because every insurer selling a given plan letter has to cover the exact same benefits, one chart works for the entire market. This is the standardized benefit structure the federal government requires — the same chart, in substance, that you'd find in Medicare's own "Choosing a Medigap Policy" guide.

Benefit ABCDF₁G₁KLMN
Part A coinsurance & hospital costs (up to 365 extra days) ✓✓✓✓✓✓✓✓✓✓
Part B coinsurance or copayment ✓✓✓✓✓✓50%75%✓✓²
Blood (first 3 pints) ✓✓✓✓✓✓50%75%✓✓
Part A hospice coinsurance or copayment ✓✓✓✓✓✓50%75%✓✓
Skilled nursing facility coinsurance ——✓✓✓✓50%75%✓✓
Part A deductible —✓✓✓✓✓50%75%50%✓
Part B deductible ——✓—✓—————
Part B excess charge ————✓✓————
Foreign travel emergency (plan limits apply) ——80%80%80%80%——80%80%
Out-of-pocket yearly limit³ N/AN/AN/AN/AN/AN/A$8,000$4,000N/AN/A

Scroll sideways on a phone or narrow screen to see every column.

₁ Plans C and F are closed to anyone who became newly eligible for Medicare on or after January 1, 2020. Plans F and G are also available in a high-deductible version in some states, requiring $2,950 (2026) in out-of-pocket costs before the plan pays anything.

² Plan N pays 100% of Part B coinsurance, except for a copay of up to $20 for some office visits and up to $50 for emergency room visits that don't result in admission.

³ For Plans K and L, once you've met the yearly out-of-pocket limit and the annual Part B deductible, the plan pays 100% of covered services for the rest of that calendar year.

Why Two People Can Pay Very Different Premiums

Since benefits are standardized, price is where Medigap plans actually compete — and pricing depends on which of three methods an insurer uses:

Community-rated

Everyone with the same plan pays the same premium regardless of age. Rates can still rise over time due to inflation or medical costs, just not because you personally got older.

Issue-age-rated

Your premium is based on your age when you first bought the policy and doesn't increase simply because you age further — though it can still rise for other reasons.

Attained-age-rated

Your premium is based on your current age each year, so it's typically the lowest starting price but tends to increase as you get older — this is the most common pricing method in the market, and one that catches some people off guard later on.

Which method a given company uses varies by state and insurer, so it's worth asking directly rather than assuming.

Your One-Time Open Enrollment Window

This is one of the most commonly misunderstood parts of Medigap: your Medicare Supplement Open Enrollment Period is not the same as the Annual Enrollment Period every fall. That fall window applies to Medicare Advantage and Part D plans only — it has no effect on Medigap.

Your actual Medigap open enrollment window begins the month your Part B coverage starts, and lasts six months. During this one-time window, an insurance company must accept you into any Medigap plan they sell, at their standard rate, with no health questions and no waiting period for pre-existing conditions. If you delay Part B because you're still working, this window opens later, whenever your Part B coverage actually begins — not necessarily at age 65. People who qualify for Medicare early due to disability get a second such window when they turn 65.

Once this window closes, applying for a Medigap policy in most states means answering health questions, and the insurer can decline your application or charge more based on your health history — except in specific guaranteed-issue situations.

Guaranteed Issue Rights

Outside your original enrollment window, certain situations still require an insurer to accept you regardless of health, usually for a short window of around 63 days. Common triggers include:

  • Losing employer or union group health coverage that was paying primary to Medicare
  • Your Medicare Advantage plan leaving your area, or you moving outside its service area
  • Trying Medicare Advantage for the first time and switching back to Original Medicare within 12 months (a one-time "trial right")
  • Your Medigap insurer becoming insolvent or misrepresenting your coverage

Plan choices during a guaranteed-issue window are often more limited than during your original open enrollment period, and the specific rules vary by state. It's worth confirming your options with a licensed agent as soon as a qualifying event happens, since these windows are short and don't reopen.

Medigap and Medicare Advantage Don't Mix

You can't have a Medicare Supplement policy and a Medicare Advantage plan active at the same time — they're two different paths to receiving your Medicare benefits, not complementary coverage. If you switch from Medigap to Medicare Advantage and later change your mind, getting back into a Medigap policy typically means going through medical underwriting again, unless you qualify for one of the guaranteed-issue situations above.

Comparing Your Two Main Paths

Both Medigap and Medicare Advantage are legitimate ways to structure your coverage, and neither is objectively better — they trade off differently, and the right fit depends on your own priorities.

Medicare Supplement (Medigap)

  • No provider network — use any doctor or hospital that accepts Medicare, anywhere in the country
  • Highly predictable costs once you've paid your premium and any deductible
  • No routine dental, vision, hearing, or gym benefits included
  • Requires a separate Part D plan for drug coverage
  • Premiums are typically higher, and can rise with age depending on the pricing method

Medicare Advantage

  • Care runs through a network of contracted providers
  • Costs vary by service through copays, with an annual out-of-pocket maximum
  • Often includes extras like dental, vision, hearing, or gym benefits
  • Usually bundles in Part D drug coverage
  • Premiums are often lower, sometimes $0 beyond the Part B premium

Questions Worth Asking Before You Choose

  • How important is it to you to see any doctor, anywhere, without checking a network first?
  • Would you rather pay a higher, predictable premium, or a lower premium with more variable costs as you use care?
  • Do you split time between states or travel often during the year?
  • Are routine dental, vision, or hearing benefits something you'd want bundled in, or are you comfortable arranging those separately?
  • Is this decision happening during your one-time open enrollment window, or would you be subject to medical underwriting?

Common Questions

Can I switch Medigap companies later if I find a better rate?

Yes, but outside your one-time open enrollment window or a guaranteed-issue situation, the new company can ask health questions and may decline your application or charge more. A few states have their own additional rules that make switching easier — it's worth checking what applies where you live.

Does my Medigap policy cover my spouse?

No. Medigap policies are individual — each person on Medicare needs their own policy, even if you're married. Some insurers offer a discount if both spouses enroll with the same company.

Is there an annual enrollment period for Medigap, like there is for Medicare Advantage?

No. There's no annual lock-in or yearly election window for Medigap. You can apply to change plans at any time, though you may face medical underwriting outside your original window or a guaranteed-issue event.

Can I still get Plan F?

Only if you were eligible for Medicare before January 1, 2020. If you became eligible on or after that date, Plan F and Plan C aren't available to you, though Plan G offers very similar coverage.

Medigap plans are standardized, but your situation isn't — timing, health history, budget, and how you like to access care all factor into whether this path or Medicare Advantage makes more sense for you. Reviewing the specifics with a licensed agent, particularly around your enrollment timing, is the best way to avoid an avoidable mistake.