Last updated: May 2025 • 11 min read
Original Medicare (Parts A and B) covers about 80% of your healthcare costs — leaving you exposed to significant out-of-pocket expenses including deductibles, copays, and coinsurance that can add up to thousands per year. Medicare Supplement insurance (also called Medigap) fills those gaps.
But with 10 standardized plan types (A through N) and dozens of insurance companies selling them, choosing the right Medigap plan is genuinely confusing. This guide makes it simple.
Medigap is private health insurance that works alongside your Original Medicare (Parts A and B). It does NOT replace Medicare — it supplements it by paying some or all of your out-of-pocket Medicare costs.
Key facts:
| Benefit | Plan A | Plan G ⭐ | Plan N | Plan K | Plan L |
|---|---|---|---|---|---|
| Part A coinsurance & hospital costs (up to 365 days) | ✓ | ✓ | ✓ | 50% | 75% |
| Part B coinsurance or copayment | ✓ | ✓ | ✓* | 50% | 75% |
| Blood (first 3 pints) | ✓ | ✓ | ✓ | 50% | 75% |
| Part A hospice care coinsurance | ✓ | ✓ | ✓ | 50% | 75% |
| Skilled nursing facility coinsurance | ✗ | ✓ | ✓ | 50% | 75% |
| Part A deductible ($1,632/2025) | ✗ | ✓ | ✓ | 50% | 75% |
| Part B deductible ($257/2025) | ✗ | ✗ | ✗ | ✗ | ✗ |
| Part B excess charges | ✗ | ✓ | ✗ | ✗ | ✗ |
| Foreign travel emergency | ✗ | 80% | 80% | ✗ | ✗ |
*Plan N: You pay copays up to $20 for office visits, up to $50 for ER visits that don't result in inpatient admission.
Plan F was the most comprehensive Medigap plan — it covered everything including the Part B deductible. However, it's no longer available to anyone who became eligible for Medicare after January 1, 2020. If you had Plan F before that date, you can keep it. For new enrollees, the choice is between Plan G and Plan N.
Plan G covers everything Plan F did except the Part B deductible ($257 in 2025). This is the only gap. In exchange, Plan G premiums are significantly lower than Plan F was — typically $600–$1,200/year cheaper. The math almost always favors Plan G over the old Plan F.
Best for: Most Medicare beneficiaries. Predictable costs, maximum coverage, freedom to see any Medicare provider.
Monthly premium range: $100–$220 (depending on age, location, insurer)
Plan N is similar to Plan G but with two differences: you pay up to $20 for office visits and up to $50 for ER visits that don't lead to admission, AND Plan N doesn't cover Part B excess charges (what non-participating doctors can charge above Medicare rates).
Best for: Relatively healthy beneficiaries who don't visit doctors frequently and don't mind some out-of-pocket copays. Typically $20–$50/month less than Plan G.
Monthly premium range: $75–$175
| Age | Plan G Monthly Premium | Plan N Monthly Premium | Plan K Monthly Premium |
|---|---|---|---|
| 65 | $100–$160 | $75–$130 | $45–$75 |
| 70 | $120–$190 | $90–$155 | $55–$90 |
| 75 | $145–$230 | $110–$190 | $68–$110 |
| 80 | $180–$285 | $140–$235 | $85–$140 |
| 85 | $220–$350 | $175–$290 | $105–$175 |
Since plans are standardized by benefit, compare companies on price, financial strength, rate increase history, and customer service.
| Company | AM Best Rating | Known For | Rate Stability |
|---|---|---|---|
| AARP / UnitedHealthcare | A | Largest enrollment; community-rated in most states | Good |
| Mutual of Omaha | A+ | Competitive rates; strong agent network | Excellent |
| Cigna | A | Competitive Plan N rates | Good |
| Humana | A- | Household discounts; broad availability | Fair |
| Blue Cross Blue Shield | A | Strong local presence; name recognition | Varies by state |
| Transamerica | A | Competitive rates for younger enrollees | Good |
This is the most important timing decision in Medicare. You have a 6-month Medigap Open Enrollment Period that begins the month you're both age 65 and enrolled in Medicare Part B.
During this window:
Apply during your Open Enrollment window, even if you're not sure you need Medigap now. Once the window closes, you may be locked out if you develop a health condition.
Many new Medicare beneficiaries confuse Medigap with Medicare Advantage (Part C). They're fundamentally different:
| Medigap | Medicare Advantage | |
|---|---|---|
| Works with | Original Medicare (A+B) | Replaces Original Medicare |
| Doctor choice | Any Medicare provider in US | Network limited in most plans |
| Premium | $75–$350/month + Part B premium | Often $0 (but Part B premium still required) |
| Out-of-pocket risk | Very low (predictable) | Higher (copays, deductibles) |
| Prescription drugs | Not included (need Part D) | Usually included |
| Extra benefits | None beyond Medicare | Often includes dental, vision, hearing |
| Best for | Frequent healthcare users; want predictability | Healthy beneficiaries; tight budgets |
Yes, but outside of guaranteed issue periods you'll need to pass medical underwriting. If your health has declined, you may be denied or charged more. This is why enrolling in the best plan during Open Enrollment is critical.
No. For drug coverage, you need a separate Medicare Part D plan. When you enroll in Medigap, also shop for a Part D prescription drug plan.
Plan G for most people. It covers nearly everything, accepts any Medicare provider nationwide, and has predictable costs. For healthier seniors comfortable with small copays, Plan N offers similar coverage at 15–25% lower premiums.
For most new Medicare enrollees in 2025, Plan G from Mutual of Omaha, AARP/UnitedHealthcare, or your state's Blue Cross Blue Shield is the safest choice. Shop during your 6-month Open Enrollment window when you're guaranteed acceptance, compare premiums from at least 3–4 insurers, and check rate increase history before committing.
Medigap costs more upfront than Medicare Advantage, but it delivers something valuable that no network-based plan can: the freedom to see any doctor anywhere in the country, with predictable, near-zero out-of-pocket costs for covered services.