Quick Summary
The core idea: Original Medicare (Parts A and B) covers a lot, but it leaves significant gaps — deductibles, co-payments, and coinsurance that can add up to thousands of dollars in a serious health event. Medicare Supplement plans are private insurance policies that fill in those gaps. They don't replace Medicare — they work alongside it.
What Is Original Medicare — and What Are Its Gaps?
Medicare Part A covers hospital care: inpatient hospital stays, skilled nursing facility care (following a qualifying hospital stay), hospice care, and some home health services.
Medicare Part B covers outpatient care: physician visits and outpatient services, preventive services, durable medical equipment, and some home health services.
What Original Medicare does not cover (the gaps):
- Medicare Part A deductible: $1,632 per benefit period in 2024 (resets for each new benefit period)
- Medicare Part B deductible: $240/year in 2024
- Medicare Part B coinsurance: 20% of the Medicare-approved amount for most services — with no out-of-pocket maximum
- Skilled nursing facility coinsurance: $194.50/day for days 21–100
- Foreign travel emergency care
- Long-term custodial care (nursing home care when not for skilled rehabilitation)
- Prescription drugs (covered separately by Medicare Part D)
The absence of an out-of-pocket maximum under original Medicare Part B is a significant exposure. If your parent has a serious illness requiring extensive outpatient treatment, the 20% coinsurance with no cap can quickly reach tens of thousands of dollars.
What Is a Medicare Supplement (Medigap) Plan?
A Medicare Supplement plan is a private insurance policy that helps pay some or all of the costs that Original Medicare doesn't cover.
Key facts:
- Medigap policies are standardized by the federal government. A Plan G from Company A covers exactly the same services as a Plan G from Company B. The only differences are premium price and company reputation.
- Medigap works alongside Original Medicare — it does not replace it. You must have Medicare Parts A and B to purchase a Medigap plan.
- Medigap plans do not cover prescription drugs. That's Medicare Part D.
- Medigap plans do not cover most dental, vision, or hearing care.
- You pay a monthly premium for your Medigap plan in addition to the standard Medicare Part B premium.
The Medicare Supplement Plan Types (A Through N)
Plan A — Basic Coverage
The most basic Medigap plan. Covers Medicare Part A coinsurance and hospital costs, Part B coinsurance or copayment, blood (first 3 pints), and Part A hospice care coinsurance.
Does not cover: Part A or B deductibles, skilled nursing facility coinsurance, foreign travel emergency.
Who it's for: People who want very basic coverage at the lowest possible premium.
Plan B
Covers everything Plan A covers, plus the Medicare Part A deductible.
Does not cover: Part B deductible, skilled nursing facility coinsurance, foreign travel emergency.
Plan C (Not available to new Medicare enrollees after January 1, 2020)
Covered everything Plan B covers, plus Part B deductible and skilled nursing facility coinsurance. If your parent enrolled in Medicare before January 1, 2020 and has Plan C, they may keep it.
Plan D
Covers everything Plan A covers, plus the Part A deductible, skilled nursing facility coinsurance, and foreign travel emergency (80%, up to plan limits).
Does not cover: Part B deductible, Part B excess charges.
Plan F (Not available to new Medicare enrollees after January 1, 2020)
Plan F was historically the most comprehensive Medigap plan, covering all standard Medicare gaps including both deductibles. Like Plan C, it was eliminated for new enrollees beginning January 1, 2020.
Plan G — Most Comprehensive Plan for New Enrollees
Plan G is currently the most comprehensive Medicare Supplement plan available to new Medicare enrollees. It covers:
- Part A coinsurance and hospital costs
- Part B coinsurance or copayment
- Part A deductible
- Skilled nursing facility care coinsurance
- Blood (first 3 pints)
- Part A hospice coinsurance
- Foreign travel emergency (80%, up to plan limits)
- Part B excess charges
Does not cover: The Medicare Part B deductible ($240/year in 2024).
Why Plan G is so popular: Plan G covers almost everything except the Part B deductible — a defined $240/year gap. For people who want comprehensive coverage and predictable out-of-pocket costs, Plan G is the standard recommendation for new enrollees.
Plan G is also available in a High-Deductible Plan G variant, which has a lower monthly premium but requires a $2,800 annual deductible (2024) before Medigap benefits begin.
Plan K
A cost-sharing plan that covers 50% of many Medicare cost-sharing amounts. Lower monthly premium than comprehensive plans and an annual out-of-pocket limit ($7,060 in 2024).
Plan L
Similar to Plan K but covers 75% of cost-sharing amounts. Annual out-of-pocket limit of $3,530 in 2024.
Plan M
Covers everything Plan A covers, plus 50% of the Part A deductible, skilled nursing facility coinsurance, and foreign travel emergency (80%).
Plan N
One of the more popular mid-tier plans. Covers Part A coinsurance, Part B coinsurance (except up to $20 copay for office visits, $50 for ER), Part A deductible, skilled nursing facility coinsurance, and foreign travel emergency.
Who it's for: Relatively healthy seniors who want strong coverage for major expenses but are comfortable paying small copays for routine visits. Plan N typically has a lower monthly premium than Plan G.
Medigap Plan Coverage at a Glance
| Benefit | A | B | D | G | K | L | M | N |
|---|---|---|---|---|---|---|---|---|
| Part A coinsurance + hospital | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| Part B coinsurance | Yes | Yes | Yes | Yes | 50% | 75% | Yes | Yes* |
| Part A deductible | No | Yes | Yes | Yes | 50% | 75% | 50% | Yes |
| Part B deductible | No | No | No | No | No | No | No | No |
| Skilled nursing coinsurance | No | No | Yes | Yes | 50% | 75% | Yes | Yes |
| Part B excess charges | No | No | No | Yes | No | No | No | No |
| Foreign travel emergency | No | No | 80% | 80% | No | No | 80% | 80% |
*Plan N covers Part B coinsurance except up to $20 copay for office visits and $50 for ER visits.
Medicare Supplement vs. Medicare Advantage: What's the Difference?
Medicare Supplement (Medigap): Works alongside Original Medicare (Parts A and B). Generally provides more flexibility — you can see any doctor who accepts Medicare, anywhere in the U.S. Monthly premium in addition to Part B premium. Does not cover prescription drugs (add Part D separately).
Medicare Advantage (Part C): An alternative to Original Medicare that bundles Parts A, B, and usually D into one plan. Often includes extra benefits (dental, vision, hearing). Usually has a network of doctors and hospitals. May have lower monthly premiums but typically has copays at time of service. Cannot hold a Medigap plan while enrolled in Medicare Advantage.
The choice between Medicare Supplement and Medicare Advantage is highly individual and depends on your parent's health status, the availability of trusted doctors in the local Medicare Advantage network, and their tolerance for out-of-pocket cost variability. This is a decision that benefits from consultation with a licensed insurance broker or SHIP counselor.
When Can My Parent Enroll in a Medicare Supplement Plan?
Open Enrollment Period
The best time to enroll is during the Medigap Open Enrollment Period: the 6-month period beginning the first month a person is both age 65 or older AND enrolled in Medicare Part B.
During this period, insurance companies must sell your parent any Medigap policy they offer — at the same premium they would charge a healthy person, regardless of pre-existing conditions.
Outside Open Enrollment
Outside the open enrollment period, insurance companies in most states can use medical underwriting— they can review your parent's health history and decline coverage or charge higher premiums based on pre-existing conditions. Exceptions exist for certain qualifying events (called "guaranteed issue rights").
Where to Get Help Choosing
- SHIP (State Health Insurance Assistance Program): Every state has a SHIP program staffed by trained counselors who provide free, unbiased Medicare counseling. Find your state's SHIP at shiphelp.org or call 1-877-839-2675.
- Medicare website: medicare.gov/medigap includes a plan comparison tool and enrollment information.
- Licensed insurance brokers: A Medicare-licensed broker can compare premiums from multiple carriers for the same plan type.
A Note on What Medicare Does Not Cover for Aging in Place
Significant categories of aging-in-place care that Medicare does not cover at all, regardless of supplemental insurance:
- Personal care / custodial care (help with bathing, dressing, cooking): Not covered by Medicare or any Medigap plan
- Long-term nursing home care: Medicare covers short-term skilled nursing; it does not cover ongoing custodial nursing home care
- Home modifications (grab bars, stair lifts, ramps): Not covered by Medicare
- Medical alert systems: Not covered by standard Medicare; some Medicare Advantage plans include them
Our Complete Caregiver's Guide covers the broader financial planning picture.
Frequently Asked Questions
What is the difference between Medicare Supplement Plan F and Plan G?
Plan F covered the Medicare Part B deductible in addition to everything Plan G covers. Plan F was eliminated for new Medicare enrollees starting January 1, 2020. The difference in cost is the Part B deductible ($240 in 2024) — Plan G does not cover it.
Does Medicare Supplement cover dental, vision, or hearing?
No. Standard Medicare Supplement plans do not cover dental, vision, or hearing care. These require separate supplemental plans or Medicare Advantage plans that include these benefits.
Can I change my Medicare Supplement plan after I enroll?
Yes, but outside of the Open Enrollment Period and guaranteed issue situations, insurers in most states can medically underwrite your application. Timing matters significantly for Medigap enrollment decisions.
Does Medicare Supplement cover care outside the United States?
Plans D, G, M, and N cover foreign travel emergency care at 80% (up to plan limits, after a small deductible). Plans A, B, K, and L do not.
Next read: Complete Caregiver's Guide for Aging Parents | 12 Home Modifications for Aging in Place | Best Medical Alert Systems of 2026