Understanding Medicare Coverage and Program Basics

What Medicare Is and How It Works

Medicare is a federal health insurance program run by the Centers for Medicare and Medicaid Services (CMS), a part of the U.S. Department of Health and Human Services. It primarily serves people age 65 and older, though some younger people with disabilities or end-stage renal disease may also receive Medicare coverage. As of 2024, more than 68 million Americans are enrolled in Medicare, making it one of the largest health insurance programs in the country.

The program operates as a social insurance system, meaning it's funded through payroll taxes that workers and employers contribute throughout their working years. This funding model differs from means-tested programs that base benefits on income level. When you turn 65, you become part of this system and can learn about the different ways Medicare covers hospital stays, doctor visits, prescription drugs, and other medical services.

Medicare has four main parts, each covering different services. Part A covers inpatient hospital care, skilled nursing facility care, hospice, and some home health services. Part B covers outpatient medical services, including doctor visits, tests, and preventive care. Part D covers prescription drug costs. Part C, also called Medicare Advantage, is an alternative way to receive Parts A and B benefits through private insurance companies that contract with Medicare.

Understanding how Medicare works involves knowing that it doesn't cover everything. Some services like long-term custodial care, dental work, hearing aids, and vision correction are typically not covered by Original Medicare (Parts A and B). This is why many people choose to purchase supplemental coverage or enroll in Medicare Advantage plans that may include additional benefits.

Practical Takeaway: Medicare is a federal insurance program with four parts that cover different medical services. Knowing which services each part covers helps you understand what costs you might owe out of pocket and what protections the program provides.

Medicare Part A: Hospital Insurance Coverage

Medicare Part A is hospital insurance that covers inpatient hospital stays, skilled nursing facility care after hospitalization, hospice services, and certain home health services. Most people don't pay a monthly premium for Part A if they or their spouse paid Medicare payroll taxes for at least 10 years (40 quarters) during their working years. However, there are costs associated with using Part A services.

When you're admitted to a hospital under Part A, you'll pay a deductible for each benefit period. In 2024, this deductible is $1,632 for each benefit period. A benefit period begins when you're admitted to the hospital and ends 60 days after you leave the hospital without being admitted again. If you're admitted after that 60-day window closes, a new benefit period starts and you pay another deductible.

Part A also includes copayment requirements during hospital stays. For days 1-60 of a hospital stay in each benefit period, you pay the deductible but no copayment. For days 61-90, you pay $408 per day in 2024. If your hospital stay exceeds 90 days, you can use "lifetime reserve days" (up to 60 total), paying $816 per day. Once you've used all your lifetime reserve days, you pay the full cost of hospitalization.

Skilled nursing facility (SNF) care is covered under Part A but only after you've been hospitalized for at least three consecutive days and only at a Medicare-certified facility. The first 20 days are covered with no copayment. Days 21-100 require a copayment of $204 per day in 2024. After day 100 in each benefit period, you pay the full cost. Home health services covered by Part A include skilled nursing care, physical therapy, occupational therapy, and speech therapy, but only for homebound patients receiving these services under a doctor's care.

Hospice care is covered by Part A for people with terminal illnesses who have a life expectancy of six months or less, as certified by a physician. Part A covers hospice services including pain management, symptom relief, and supportive services. You pay nothing for hospice care itself, though you may have small copayments for drugs and respite care.

Practical Takeaway: Part A covers hospital and post-hospital care with significant out-of-pocket costs based on how long you're hospitalized. Understanding the deductible and copayment structure helps you anticipate costs and plan for supplemental coverage if needed.

Medicare Part B: Medical Insurance and Outpatient Services

Medicare Part B covers outpatient medical services including doctor visits, diagnostic tests, preventive care, medical equipment, and hospital outpatient department services. Unlike Part A, Part B requires a monthly premium that most people pay. The standard Part B premium in 2024 is $174.70 per month, though higher-income beneficiaries pay more through an income-related adjustment.

Part B also has an annual deductible of $240 in 2024. Once you meet this deductible, Medicare typically pays 80% of approved charges for most services, and you pay the remaining 20%. This 20% coinsurance can add up significantly, especially for ongoing medical care. For example, if you see a specialist who charges $200 for a visit and Medicare approves $150, you'd pay 20% of $150 ($30) after meeting your deductible, even though the actual charge was higher. The difference between the approved amount and the actual charge is written off by providers who accept Medicare assignment.

Preventive services covered by Part B include annual wellness visits, cancer screenings (mammograms, colonoscopies, pap smears), cardiovascular disease screenings, diabetes screening, bone density testing, and vaccinations. These preventive services are covered at no cost when provided by an in-network provider. However, if your preventive visit becomes a regular office visit because you discuss an existing problem, you may owe Part B coinsurance.

Part B also covers durable medical equipment (DME) including wheelchairs, walkers, oxygen equipment, and diabetic supplies. Medicare pays 80% of the approved amount after you meet your Part B deductible. Mental health services including therapy and psychiatric care are covered under the same 80/20 split. Substance abuse treatment, including both inpatient and outpatient services, is also covered by Part B.

Important limitations exist for certain services. Physical therapy and occupational therapy are limited to 60 sessions per year combined, with some exceptions. Speech language pathology services have a separate 60-session annual limit. Mental health services previously had visit limitations, but recent changes have removed some of these restrictions. Chiropractic care is limited to manipulation of the spine, and only for specific conditions. Acupuncture now has limited coverage for chronic lower back pain.

Practical Takeaway: Part B covers doctor visits and outpatient services with a monthly premium, annual deductible, and 20% coinsurance on most services. Knowing what preventive care is free and what services have limitations helps you make informed decisions about your medical care.

Medicare Part D: Prescription Drug Coverage

Medicare Part D provides prescription drug coverage through private insurance plans contracted with Medicare. Unlike Parts A and B, Part D is completely optional, but people who don't enroll when first becoming part of Medicare and who go without creditable drug coverage (coverage as good as Medicare Part D) may pay a penalty. The penalty is calculated as 1% of the national base beneficiary premium for each month you're not covered, added permanently to your Part D premium. In 2024, this could mean paying an extra $7 to $10 per month for life.

Part D coverage has a specific payment structure that changes throughout the year. In 2024, you first pay a monthly premium to your chosen plan. After that, you pay 25% of drug costs until you reach $545 in total drug costs (not what you pay, but what your plan pays and you pay combined). Once you hit $545, you enter the coverage gap, where you pay a higher percentage—typically around 25% of brand-name drugs and 25% of generic drugs through the end of the calendar year. The Inflation Reduction Act has made significant changes to Part D costs, with capped out-of-pocket costs and no cost-sharing for vaccines.

Each Part D plan has a formulary, which is the list of drugs it covers. Plans must cover certain drugs in protected categories including cancer drugs, anticonvulsants, antiretrovirals, and immunosuppressants. However