For most seniors, Original Medicare alone leaves significant financial gaps. It covers hospital stays and doctor visits but excludes dental care, vision, hearing aids, and long-term care entirely. Even for covered services, the deductibles, coinsurance, and daily charges during extended hospital stays can add up to thousands of dollars per year. The vast majority of Medicare beneficiaries carry some form of supplemental coverage to fill these holes.
What Original Medicare Actually Covers
Medicare Part A covers inpatient hospital stays, skilled nursing facility care (with limits), hospice, and some home health services. Part B covers doctor visits, outpatient care, preventive screenings, and medically necessary equipment. Together, they form a solid foundation, but the cost-sharing structure leaves you exposed in ways that surprise many people.
The standard Part B premium in 2025 is $185 per month, with a $257 annual deductible. After that, you typically pay 20% of the Medicare-approved amount for most services, with no annual cap on what that 20% can total. A single expensive surgery or cancer treatment can generate thousands in coinsurance alone.
Part A has its own costs. Each time you’re admitted to the hospital, you face a deductible of $1,736 per benefit period. Days 1 through 60 are then covered in full, but if your stay stretches longer, the daily charges climb fast: $434 per day for days 61 through 90, and $868 per day after that using a limited pool of 60 “lifetime reserve days.” Once those reserve days are gone, Medicare pays nothing.
Major Services Medicare Doesn’t Cover
The exclusions list is where Original Medicare falls shortest for everyday senior healthcare. It does not cover routine dental care, including cleanings, fillings, extractions, or dentures. It does not cover eye exams for glasses or the glasses themselves. It does not cover hearing exams for fitting hearing aids, or the hearing aids. These are three of the most common healthcare needs among older adults, and none of them are included.
There are narrow exceptions on the dental side. Medicare may pay for dental services directly related to a heart valve replacement, organ transplant, cancer treatment, or dialysis. But a standard cavity filling or set of dentures? Entirely out of pocket.
The other glaring gap is long-term care. Medicare does not cover assisted living, custodial nursing home stays, or ongoing help with daily activities like bathing and dressing. It covers skilled nursing facility care only after a qualifying hospital stay, and only for up to 100 days per benefit period. For days 21 through 100, you pay $217 per day in coinsurance. After day 100, you pay everything. Given that the average nursing home stay often extends well beyond 100 days, this is one of the largest financial risks seniors face.
Prescription Drug Costs Under Part D
Original Medicare (Parts A and B) does not include outpatient prescription drug coverage. You need a separate Part D plan for that, which carries its own monthly premium, deductible, and copays.
A major improvement took effect in 2025 thanks to the Inflation Reduction Act: Part D now has a $2,000 annual cap on out-of-pocket spending for covered drugs. Before this change, seniors taking expensive medications could spend far more, especially during the notorious “coverage gap” phase. That gap has been eliminated. For people on multiple brand-name prescriptions or specialty drugs, this cap is a meaningful safeguard. Still, Part D premiums vary widely by plan, and not every drug is on every plan’s formulary.
Higher Premiums for Higher Earners
If your income is above certain thresholds, Medicare charges more. This surcharge, called the Income-Related Monthly Adjustment Amount, applies to both Part B and Part D premiums. For 2025, individuals earning $106,000 or less (or couples filing jointly at $212,000 or less) pay the standard $185 monthly Part B premium.
Above that, premiums rise in tiers. An individual earning between $133,000 and $167,000 pays $370 per month for Part B, double the standard rate. At the highest bracket ($500,000 or more for individuals, $750,000 for couples), the Part B premium reaches $628.90 per month. Part D carries its own surcharges on the same income brackets, adding up to $85.80 per month at the top. These adjustments are based on your tax return from two years prior, so a one-time spike in income from selling a home or taking a large retirement distribution can trigger higher premiums you might not expect.
How Supplemental Coverage Fills the Gaps
Most Medicare beneficiaries recognize these gaps and add some form of extra coverage. As of 2021, 14.6 million beneficiaries were enrolled in Medigap (Medicare Supplement Insurance) plans, which are specifically designed to cover deductibles, coinsurance, and copayments that Original Medicare leaves behind. Medigap plans are sold by private insurers and come in standardized letter-designated options (Plan G, Plan N, etc.), each covering a different combination of costs.
The alternative is Medicare Advantage (Part C), which replaces Original Medicare with a private plan that often bundles medical, drug, and sometimes dental and vision coverage into one package. Medicare Advantage plans typically have annual out-of-pocket maximums, which Original Medicare lacks. The tradeoff is that most Advantage plans use provider networks, meaning you may need referrals or face higher costs for out-of-network care.
Choosing between Medigap and Medicare Advantage comes down to how you use healthcare. If you travel frequently within the U.S., see specialists without referrals, and want predictable costs, Medigap paired with a standalone Part D plan gives you the most flexibility. If you want lower premiums and are comfortable staying within a network, Medicare Advantage can bundle more benefits at a lower monthly cost, though with more restrictions on which doctors you see.
Medicare and Travel Abroad
Original Medicare provides almost no coverage outside the United States. In most situations, it will not pay for any healthcare or prescriptions you receive in another country. The only exceptions involve emergencies where a foreign hospital is closer than the nearest U.S. hospital, or medical emergencies while traveling through Canada on a direct route between Alaska and another state. Medicare also won’t cover care on a cruise ship that’s more than six hours from a U.S. port.
If you travel internationally, most Medigap plans (including the popular G and N options) include foreign travel emergency coverage. They pay 80% of emergency care costs abroad after a $250 annual deductible, up to a $50,000 lifetime limit. That’s helpful for emergencies but won’t cover routine care or extended treatment overseas. Seniors who spend significant time abroad often purchase separate travel medical insurance.
Where the Biggest Financial Risks Remain
Even with supplemental coverage, two categories of expense remain largely unaddressed. The first is long-term care. Neither Medicare, Medigap, nor most Medicare Advantage plans cover custodial care in a nursing home or assisted living facility. Long-term care insurance exists as a separate product, but premiums are high and rise with age, making it difficult to purchase later in life.
The second is dental care beyond basic cleanings. A single dental implant can cost several thousand dollars. Full dentures, root canals, and periodontal treatment add up quickly. Some Medicare Advantage plans include limited dental benefits, and standalone dental insurance for seniors is available, but coverage limits are often low relative to the cost of major procedures.
Original Medicare provides a strong baseline, covering the most expensive categories of care: hospitalizations, surgeries, cancer treatment, and physician services. But calling it “enough” depends entirely on your health, your supplemental coverage, and your tolerance for financial risk. For most seniors, it works best as one layer of protection rather than the only one.