Medicare covers a lot — but not everything. The gaps in Original Medicare (deductibles, coinsurance, copays) can add up to thousands of dollars per year for people who use healthcare regularly. Medicare Supplement insurance, commonly called Medigap, fills those gaps. But with 10 standardized plan types and significant premium variation between insurers, choosing the right Medigap plan requires understanding what you're actually buying. This guide explains every major plan type, compares the most popular options, and shows you how to find the best premium for your situation.
Original Medicare (Parts A and B) pays for most but not all of your covered healthcare costs. You're left responsible for deductibles, copays, and coinsurance — costs that can be unpredictable and substantial if you need significant care.
Medicare Supplement insurance (sold by private insurers, regulated and standardized by federal and state governments) pays some or all of those remaining costs. You continue to have Original Medicare as your primary coverage; Medigap is secondary. Every Medicare-accepting doctor and hospital in the country accepts Medigap — there are no networks, no referral requirements, and no pre-authorization requirements for covered services.
In 2026, approximately 14 million Medicare beneficiaries have Medigap coverage. Monthly premiums range from about $80/month for the most basic plans to $400+/month for comprehensive plans in high-cost states, depending primarily on age, plan type, tobacco use, and state of residence.
Before choosing a Medigap plan, it helps to understand exactly what costs Original Medicare leaves you responsible for:
| Medicare Gap | 2026 Amount | When It Applies |
|---|---|---|
| Part A deductible | $1,632 | Each hospital benefit period (not per year) |
| Part A coinsurance (days 61–90) | $408/day | Each hospital day after 60 |
| Part A coinsurance (days 91–150) | $816/day | Lifetime reserve days |
| Skilled nursing facility coinsurance | $204/day | Days 21–100 of SNF stay |
| Part B deductible | $257/year | Annual, before Part B kicks in |
| Part B coinsurance | 20% of approved costs | All outpatient services, after deductible |
| Part B excess charges | Up to 15% above approved rate | When provider doesn't accept assignment |
The 20% Part B coinsurance is the biggest risk for most Medicare beneficiaries. A $100,000 cancer treatment course would leave you with a $20,000 bill. A major cardiac event requiring a $50,000 procedure would cost you $10,000 out-of-pocket. These are the costs Medigap is designed to protect against.
As of 2026, 10 standardized Medigap plans are available: A, B, C, D, F, G, K, L, M, and N. Plans C and F are no longer available to people who became eligible for Medicare on or after January 1, 2020 (they covered the Part B deductible, which was eliminated for new enrollees). The chart below shows what each plan covers:
| Benefit | A | B | D | G* | K | L | M | N |
|---|---|---|---|---|---|---|---|---|
| Part A hospital coinsurance + 365 days | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Part A deductible ($1,632) | — | ✓ | ✓ | ✓ | 50% | 75% | 50% | ✓ |
| Part B coinsurance (20%) | ✓ | ✓ | ✓ | ✓ | 50% | 75% | ✓ | ✓* |
| Part B excess charges | — | — | — | ✓ | — | — | — | — |
| Skilled nursing coinsurance | — | — | ✓ | ✓ | 50% | 75% | ✓ | ✓ |
| Foreign travel emergency | — | — | ✓ | ✓ | — | — | ✓ | ✓ |
| Out-of-pocket annual limit | — | — | — | — | $7,220 | $3,610 | — | — |
*Plan G: covers everything listed. Does NOT cover Part B deductible ($257/year). *Plan N: copays up to $20/doctor visit, up to $50/ER visit; no excess charge coverage.
Plan G is the gold standard for comprehensive Medigap coverage for people new to Medicare. After you pay the $257 Part B annual deductible, Plan G pays 100% of all Medicare-approved costs: hospital stays, surgery, doctor visits, outpatient procedures, skilled nursing facility coinsurance, and more. You also get Part B excess charge coverage (important in states like New York and California where many high-end specialists opt out of Medicare assignment) and 80% coverage of emergency healthcare outside the US.
2026 Typical Monthly Premiums for Plan G:
Your maximum annual out-of-pocket with Plan G in 2026: just the $257 Part B deductible, then nothing for covered services. This predictability is Plan G's primary advantage.
Plan N covers the same major benefits as Plan G — hospital coinsurance, Part A deductible, 20% Part B coinsurance, skilled nursing coinsurance, foreign travel emergency — with two meaningful differences:
In exchange, Plan N premiums are typically $25–$50/month lower than Plan G — $300–$600/year less. This premium savings offsets the copays if you have fewer than 15–30 office visits per year and your providers accept Medicare assignment (most do).
Who benefits most from Plan N: Relatively healthy people who see doctors occasionally but want protection against major healthcare events. The lower premium is pure savings in years with few office visits; in bad years, the copays are a modest additional cost compared to the premium savings.
High-Deductible Plan G works like Plan G in all coverage respects but requires you to pay the first $2,870 (2026 amount) of Medicare cost-sharing before Plan G coverage kicks in. After meeting that deductible, you pay nothing for covered services.
Monthly premiums for HD Plan G run $30–$65/month — dramatically lower than standard Plan G. This plan makes financial sense for people who are generally healthy and want catastrophic protection at a minimal premium — similar in concept to a high-deductible health plan with an HSA during working years.
| Feature | Plan G | Plan N |
|---|---|---|
| Monthly premium (age 65, avg.) | $145–$175 | $110–$145 |
| Part B deductible covered? | No ($257/yr) | No ($257/yr) |
| Doctor visit copay | $0 | Up to $20 |
| Emergency room copay | $0 | Up to $50 |
| Part B excess charges | Covered | NOT covered |
| Hospital coinsurance | $0 | $0 |
| Part A deductible ($1,632) | Covered | Covered |
| Skilled nursing coinsurance | Covered | Covered |
| Best for | Frequent care users, predictability | Occasional care, cost-conscious |
This is one of the most important health insurance decisions a person turning 65 makes. Both options fill Medicare's gaps — but very differently.
Medigap advantages: See any Medicare-accepting provider nationwide (no networks). Predictable costs — you know your maximum annual outlay. No pre-authorization requirements for covered services. Covers foreign travel emergencies (Plan G/N). No need to coordinate care through a primary care physician.
Medicare Advantage advantages: Lower or $0 monthly premiums (many plans have no additional premium beyond Part B). Often includes dental, vision, hearing, and fitness benefits Original Medicare doesn't cover. Drug coverage often built in (MAPD plans). Can be cost-effective for people who rarely use healthcare.
Medigap disadvantages: Higher monthly premium. No prescription drug coverage (need separate Part D plan). Switching from Medicare Advantage back to Medigap later is difficult — you'll face medical underwriting in most states.
Medicare Advantage disadvantages: Network restrictions (must use plan's network or pay out-of-network rates). Higher out-of-pocket maximums when you use care significantly ($3,500–$8,550 in 2026). Prior authorization requirements can delay or deny care. Plans can change their networks, formularies, and costs annually.
General principle: if you have significant ongoing health needs, travel frequently, or want maximum predictability, Medigap Plan G is usually the better choice financially when accounting for full cost of care. If you're generally healthy and primarily want low premiums with some ancillary benefits, Medicare Advantage may serve you well — but understand the risk of much higher costs if your health changes.
Your Medigap Open Enrollment Period (OEP) is a 6-month window that begins the month you turn 65 AND are enrolled in Medicare Part B. During this period:
This is the single most important enrollment window. Once it closes, you can be medically underwritten and denied coverage or charged significantly higher premiums based on health history (except in states with more protective rules like New York, Connecticut, Massachusetts, and a few others). If you delay Part B enrollment (because you have employer coverage), your Medigap OEP doesn't begin until you enroll in Part B.
Outside the OEP, you have guaranteed issue rights (cannot be denied or charged more) in specific situations: losing employer-sponsored coverage, moving out of your Medicare Advantage plan's service area, your Medicare Advantage plan leaving the market, or losing Medigap coverage through no fault of your own. These situations trigger a 63-day Special Enrollment Period with guaranteed issue rights.
Because all Plan G policies are standardized and provide identical coverage, the only reason to pay more for one insurer over another is service quality — and Medicare Supplement companies all pay the same claims. Premium shopping is therefore critically important:
Use our free Medicare Eligibility Checker to see when you can enroll, estimate your costs, and understand your plan options — no sign-up required.
🏥 Check My Medicare Options →