If you search “gap insurance for Medicare,” you’ll find two entirely different products: Medigap (Medicare Supplement Insurance for people 65+ on Original Medicare) and medical gap insurance (short-term policies that pay cash benefits for specific events, sold to any age group). Medigap covers Original Medicare’s cost-sharing gaps—the deductibles and coinsurance you’d otherwise pay. Medical gap insurance is an event-triggered policy, more like critical illness or accident coverage, that pays a lump sum if you’re hospitalized, regardless of your primary insurance.
This guide focuses on Medigap: what it covers, what it costs over time, and when you actually need one.
The short answer
Medigap covers Original Medicare’s cost-sharing gaps—the 20% coinsurance on Part B services, hospital deductibles, and skilled nursing coinsurance—so you pay less out-of-pocket when you use care. It does not cover dental, vision, hearing, long-term care, or prescription drugs. Whether you need it depends on whether you choose Original Medicare (where Medigap makes sense) or Medicare Advantage (where Medigap is not allowed and not needed).
What gaps do Medigap plans fill
Original Medicare (Parts A and B) covers most hospital and doctor visits, but leaves you responsible for deductibles, coinsurance, and—critically—20% of all Part B charges with no annual cap. A $50,000 hospital stay could leave you with $10,000 in coinsurance. That’s the gap.
Medigap plans are sold by private insurers but standardized by federal law into ten lettered plans (A, B, C, D, F, G, K, L, M, N). Every Plan G, for example, covers the same benefits whether you buy from Aetna or Cigna—only the premium and service differ. Here’s what the most comprehensive plans cover:
Covered by most Medigap plans:
- Part A coinsurance: Hospital days 61–90 and lifetime reserve days (91+)
- Part B coinsurance: The 20% you owe after Medicare pays 80%
- Part B deductible: $240/year in 2024 (Plan G does not cover this; Plans C and F do, but Plan F closed to new enrollees in 2020)
- Skilled nursing facility coinsurance: Days 21–100 of rehab care
- Blood transfusions: First 3 pints per year
- Hospice coinsurance
- Foreign travel emergency care: Up to 80% of costs (Plans C, D, F, G, M, N only)
All benefits are defined by the Centers for Medicare & Medicaid Services; insurers cannot change what a plan covers, only what they charge for it.
What Medigap does NOT cover:
- Dental, vision, hearing: No routine exams, cleanings, glasses, dentures, or hearing aids
- Prescription drugs: You must buy Part D separately
- Long-term custodial care: Nursing home stays beyond the 100-day skilled nursing limit are entirely out-of-pocket
- Over-the-counter items, cosmetic procedures, acupuncture (unless Original Medicare covers them first, which it rarely does)
This surprises many new enrollees. Medigap sounds like “complete coverage,” but a Plan G holder still pays full price for a root canal, progressive lenses, and hearing aids. Those costs can run hundreds to thousands per year for many retirees and are not addressed by any Medigap plan.
What Medigap costs—and what it costs over time
Premium ranges depend on your age, state, and the plan you choose. Here are representative 2024–2025 rates from major insurers; rates vary significantly by state and insurer:
Plan G (most popular comprehensive option; covers everything except the Part B deductible):
- Age 65: $120–$160/month
- Age 75: $200–$320/month
- Age 85: $350–$550/month
Plan N (covers most gaps but requires copays for doctor visits and ER):
- Age 65: $90–$130/month
- Age 75: $150–$250/month
- Age 85: $260–$420/month
Premiums typically increase 3–5% per year, compounding as you age. If you enroll in Plan G at 65 paying $150/month and experience 3% annual increases, you’ll pay roughly:
- Year 10 (age 75): $202/month
- Year 20 (age 85): $271/month
- Cumulative 20-year cost: ~$47,000
Add Part D drug coverage (average $30–$70/month) and your total Medicare premium spend over 20 years approaches $55,000–$65,000, before paying for any actual care, drugs, dental, or vision. At age 65, $150/month sounds manageable. At 85, $350–$550/month on a fixed income is a different conversation.
State variation is significant. In California, Plan G premiums at age 65 range $140–$200/month; in Florida, $120–$180; in New York (which uses community rating, not age rating), everyone pays the same premium regardless of age, so 65-year-olds pay more but 85-year-olds pay less. Not all states sell all ten plans. Always check your state’s insurance commissioner website for local pricing.
When do you need Medigap insurance
The real decision isn’t “Do I need Medigap?”—it’s “Do I choose Original Medicare + Medigap, or Medicare Advantage?” These are two different coverage paths, and Medigap only works with the first.
| Factor | Original Medicare + Medigap | Medicare Advantage (Part C) |
|---|---|---|
| Provider access | Any doctor who accepts Medicare, nationwide; no network restrictions | Must use plan’s network (HMO, PPO, or EPO); out-of-network care costs more or isn’t covered |
| Monthly premiums | Medigap: $120–$550/month; Part D: $30–$70/month | Often $0–$50/month (sometimes higher); drug coverage usually included |
| Prescription drug coverage | Separate Part D purchase required | Usually included in plan premium |
| Out-of-pocket predictability | Mostly predictable; Medigap covers most cost-sharing | Less predictable; you pay copays up to an annual out-of-pocket maximum ($8,850 federal limit in 2024) |
| Dental, vision, hearing | Not covered by Medigap | Some plans include these; varies by plan |
| Coverage gaps | No caps on covered services; no annual out-of-pocket max | Out-of-pocket max applies; covers everything up to that limit, then 100% |
When Medigap makes sense:
- You want nationwide access to any Medicare provider (you travel, you have specialists in multiple states)
- You can afford $150–$300+/month in premiums on top of Part B ($174.70/month in 2024)
- You expect significant healthcare usage and want predictable, low out-of-pocket costs
- You prefer to coordinate Medigap with employer retiree coverage
When Medicare Advantage makes sense:
- Your doctors are in-network and you don’t travel often for care
- You want lower monthly premiums (or $0-premium plans)
- You value included dental/vision/hearing coverage
- You’re healthy and expect moderate usage; the out-of-pocket max protects you if something goes wrong
Run the 20-year math for your situation. If you’re healthy and on a $0-premium Medicare Advantage plan, you might pay $500–$2,000/year total. If you’re on Plan G + Part D, you’re paying $2,400–$3,000/year in premiums alone before you see a doctor. But if you have a $40,000 hospital stay, Medigap covers nearly all of it; Medicare Advantage may leave you with $3,000–$8,850 in cost-sharing. The right answer depends on your health, income, and risk tolerance.
Enrollment timing: the window that costs money if you miss it
You can only buy Medigap guaranteed issue—meaning insurers cannot deny you or charge more based on health—during specific windows:
Initial Enrollment Period (age 65):
- The six-month period starting the month you turn 65 and enroll in Part B
- During this window, insurers must sell you any Medigap plan they offer, at standard rates, regardless of pre-existing conditions
Special enrollment (guaranteed issue after Medicare Advantage):
- If you drop a Medicare Advantage plan within the first 12 months of joining, or if your plan leaves your area
- Limited to 63 days from the triggering event
Outside these windows, insurers in most states can:
- Deny your application based on health conditions
- Charge higher premiums (medical underwriting)
- Impose waiting periods for pre-existing conditions (up to six months in some states)
Real example: enroll in Plan G at 65 during guaranteed issue, and you pay $150/month. Wait until age 70 and apply outside guaranteed issue, and that same insurer may quote $180/month base rate plus a $30–$50/month “underwriting surcharge” for a chronic condition—a penalty you pay for life.
Three states (California, Oregon, and New York) have year-round Medigap protections or birthday rules that give you additional opportunities to switch plans; most states do not. Check your state’s rules before assuming you can enroll anytime.
Switching plans or carriers
You can apply to switch Medigap plans or move to a different insurer anytime, but you are not guaranteed acceptance. Outside your initial enrollment period, insurers can require medical underwriting. If your health has declined since you first enrolled, you may be denied or charged more.
Some states allow a 30-day trial period when switching from Medicare Advantage back to Original Medicare + Medigap, but this is not universal. If you’re on Medigap and want to switch to a different Medigap plan (say, Plan G to Plan N to save money), shop carefully—your current insurer may offer a lower rate to retain you, and switching to a new carrier triggers underwriting in most states.
Federal law guarantees you the right to buy Plan A or Plan B (the most basic plans) if you’re losing employer or union coverage, but these plans offer minimal benefits compared to Plan G or N.
FAQ
What does Medigap coverage include?
Medigap covers the cost-sharing gaps in Original Medicare: hospital and medical coinsurance, deductibles, skilled nursing facility coinsurance (days 21–100), blood transfusions, and emergency care outside the U.S. (on most plans). It does not cover dental, vision, hearing, long-term custodial care, or prescription drugs.
How much does Medigap insurance cost?
Premiums vary by age, plan, state, and insurer. At age 65, expect $90–$160/month for popular plans (Plan N or Plan G). By age 85, the same plans cost $260–$550/month due to annual rate increases. Over 20 years, cumulative premiums can exceed $50,000.
Do I need Medigap if I have Medicare Advantage?
No. You cannot have both. Medicare Advantage replaces Original Medicare, so Medigap (which supplements Original Medicare) is not allowed and would be redundant. The decision is Original Medicare + Medigap vs. Medicare Advantage, not whether to add Medigap on top of Advantage.
When can I enroll in Medigap?
The best time is your six-month Initial Enrollment Period starting when you turn 65 and enroll in Part B. During this window, insurers must sell you any plan they offer, regardless of health. Outside this period, you may face denials, higher premiums, or waiting periods in most states.
What’s the difference between Medigap and Medicare Advantage?
Medigap supplements Original Medicare by covering deductibles and coinsurance; you pay a monthly premium for predictable, low out-of-pocket costs and can see any Medicare provider nationwide. Medicare Advantage replaces Original Medicare with a private plan (often HMO or PPO) that includes drug coverage and sometimes dental/vision but requires you to use a network and pay copays up to an annual out-of-pocket maximum.
Can I switch Medigap plans?
Yes, but it’s not guaranteed. You can apply to switch plans or carriers anytime, but outside your initial enrollment period, insurers can require medical underwriting and may deny you or charge more based on your health. A few states (California, Oregon, New York) offer additional protections; most do not.
Medigap is a powerful tool for managing Medicare’s cost-sharing, but it’s expensive over time, doesn’t cover everything, and locks you into a premium that rises with age. The real question is whether Original Medicare + Medigap fits your health, finances, and preferences better than Medicare Advantage. Run the 20-year math, compare networks, and enroll during your guaranteed issue window—because missing it can cost you for the rest of your retirement. For more on how supplemental insurance works across different health scenarios, see our comparison guide.
This is not insurance or financial advice. Coverage, pricing, and regulations vary by state and insurer. Consult a licensed insurance agent or your state insurance commissioner for guidance on your specific situation.