For many seniors, Original Medicare alone leaves significant financial gaps. There is no annual cap on out-of-pocket spending, several common health needs are excluded entirely, and a serious illness or long hospital stay can generate thousands of dollars in costs that Medicare does not cover. Most seniors need some form of supplemental coverage to avoid unexpected bills.
What Original Medicare Covers (and What It Costs)
Medicare Part A covers hospital stays, skilled nursing care, and hospice. Part B covers doctor visits, outpatient procedures, lab tests, and preventive screenings. In 2025, the standard Part B premium is $185 per month, with an annual deductible of $257. After that deductible, you typically pay 20% of the Medicare-approved amount for most services, with no upper limit on what that 20% can add up to over a year.
That missing spending cap is one of the biggest risks of relying on Original Medicare by itself. A single hospitalization, cancer treatment, or surgical procedure can leave you responsible for tens of thousands of dollars in coinsurance. There is no yearly limit on what you pay out of pocket unless you have supplemental coverage like a Medigap policy or a Medicare Advantage plan.
Services Medicare Does Not Cover
Original Medicare excludes several health services that seniors commonly need. Eye exams for prescription glasses, hearing aids and the exams to fit them, and most dental care (cleanings, fillings, extractions, dentures) are all left out. These aren’t minor expenses. A single pair of hearing aids can cost several thousand dollars, and dental work adds up quickly without coverage.
Medicare also does not cover most care received outside the United States. If you travel internationally and get sick, you pay the full cost yourself in almost every case. The only exceptions involve narrow emergency scenarios, such as a foreign hospital being the closest option during a medical emergency near the border. Prescription drugs purchased outside the U.S. are never covered.
Hospital Stays Can Get Expensive Fast
Part A covers the first 60 days of a hospital stay after you meet the inpatient deductible. Beyond that, costs escalate sharply. Days 61 through 90 carry a daily coinsurance of $419 in 2025. If your stay stretches past 90 days, you draw on lifetime reserve days at $838 per day, and you only get 60 of those reserve days total across your lifetime. Once they’re gone, you pay the full cost of each additional day.
For skilled nursing facility care, Medicare covers up to 100 days per benefit period, but only if you meet strict conditions: a qualifying three-day hospital stay, entry into the facility within about 30 days, and a documented need for daily skilled care like physical therapy or intravenous medications. After day 20, you owe a daily coinsurance. After day 100, coverage stops entirely. This is not long-term care. Seniors who need ongoing help with daily activities like bathing, dressing, or eating will not find that covered under any part of Medicare.
What Seniors Actually Spend Out of Pocket
A Health Affairs study found that in 2019, seniors on traditional Medicare without supplemental coverage spent an average of $579 per month out of pocket on healthcare. That works out to nearly $7,000 a year. Health status makes a dramatic difference: those in poor health spent an estimated $943 per month (over $11,300 a year), compared to $421 per month for those in excellent health.
These figures include premiums, deductibles, coinsurance, and services Medicare doesn’t cover. They illustrate why Original Medicare on its own can be a financial strain, especially for anyone managing chronic conditions or facing a serious diagnosis.
How Medigap Plans Fill the Gaps
Medigap (Medicare Supplement Insurance) policies are designed to pair with Original Medicare and pick up many of the costs it leaves behind. Depending on the plan you choose, Medigap can cover Part A and B coinsurance, hospital costs beyond day 60, the Part B deductible, and excess charges from providers who bill above the Medicare-approved amount.
Plans vary in what they cover. Plan G is one of the most popular options, covering nearly all cost-sharing except the annual Part B deductible. Plans K and L take a different approach, covering a percentage of costs but capping your annual out-of-pocket spending at $8,000 and $4,000 respectively in 2026. Plan N covers 100% of Part B costs but requires small copayments for certain office and emergency room visits. High-deductible versions of Plans F and G are available in some states, requiring you to pay $2,950 in 2026 before the policy kicks in.
Most Medigap plans also include foreign travel emergency coverage, paying 80% of emergency care costs outside the U.S. after a $250 annual deductible, up to a $50,000 lifetime limit. That’s a meaningful benefit for seniors who travel internationally. One important limitation: Medigap plans do not cover prescription drugs, dental, vision, or hearing. You need a separate Part D plan for medications.
Medicare Advantage as an Alternative
Medicare Advantage plans (Part C) bundle Part A, Part B, and usually Part D into a single plan run by a private insurer. Many also include dental, vision, and hearing benefits that Original Medicare lacks. The key structural advantage is a mandatory annual out-of-pocket cap. In 2025, that cap cannot exceed $9,350 for in-network services, though the average plan sets it around $5,320 for in-network care.
The same Health Affairs analysis found that out-of-pocket costs in Medicare Advantage were roughly 18 to 24 percent lower than in traditional Medicare without Medigap, averaging about $440 per month in 2019 compared to $579. The tradeoff is that Medicare Advantage plans typically restrict you to a network of providers and may require prior authorization for certain services. If you see out-of-network doctors frequently or want the freedom to visit any provider who accepts Medicare, Original Medicare with a Medigap plan may be a better fit despite the higher premium cost.
Prescription Drug Coverage Has Improved
Medicare Part D covers prescription drugs, but it has historically been one of the more confusing and costly parts of the program. Recent changes have introduced a meaningful cap on drug spending. Starting in 2025, once your out-of-pocket costs on covered Part D drugs reach a set threshold (rising to $2,100 in 2026), you enter catastrophic coverage and pay nothing for covered drugs for the rest of the year.
This is a significant improvement for seniors taking expensive medications. Before these changes, some beneficiaries faced thousands of dollars in costs even after reaching the catastrophic phase. The new structure effectively creates the kind of spending limit that has long been missing from other parts of Medicare.
The Long-Term Care Problem
Perhaps the biggest gap in Medicare is one that no supplement fully addresses: long-term care. Medicare does not cover custodial care, the kind of ongoing daily assistance that millions of seniors eventually need as they age. Assisted living facilities, in-home aides for non-medical help, and nursing home stays beyond the 100-day skilled care window are all excluded.
The median annual cost of a private room in a nursing home exceeds $100,000 in many parts of the country. Medicaid covers long-term care, but only for people who have spent down nearly all of their assets. Long-term care insurance is an option, but it is expensive and ideally purchased years before it’s needed. This is the single largest financial risk that Medicare, even with supplemental coverage, does not protect against.
Putting It Together
Original Medicare provides a solid foundation, but it was never designed to cover everything. The lack of an out-of-pocket maximum, the exclusion of dental, vision, and hearing care, the steep costs of extended hospital stays, and the absence of long-term care coverage all create real financial exposure. Seniors who rely on Original Medicare alone, without any supplemental plan, face average annual out-of-pocket costs approaching $7,000, and potentially much more if their health declines.
Whether you close those gaps with a Medigap policy and standalone Part D plan, or switch to a Medicare Advantage plan that bundles everything together, some form of additional coverage makes a meaningful difference. The right choice depends on your health, your budget, how often you travel, and how important provider choice is to you. What’s clear is that for most seniors, Medicare by itself is not enough.