How Does Medicare Work?

Medicare is the federal health insurance program that covers tens of millions of Americans — but how it actually works is something most people do not fully understand until they are right in the middle of enrolling. This page breaks it down clearly so you can make confident decisions about your coverage.

The Big Picture — What Medicare Actually Does

Medicare is a federal health insurance program administered by the Centers for Medicare and Medicaid Services — known as CMS. It was established in 1965 to ensure that Americans age 65 and older — as well as certain younger people with qualifying disabilities or conditions — have access to health coverage regardless of their income or employment status.

Unlike private health insurance you may have had through an employer, Medicare does not come from a single insurance company offering a single plan. It is a system made up of different parts — each covering a different category of health care — and beneficiaries make choices about how they receive their benefits based on their health needs, their budget, and the doctors and hospitals they want to use.

Understanding how Medicare works starts with understanding its structure. There are four parts to the program, and the way those parts interact determines what you pay, what is covered, and what gaps you may need to fill with additional coverage.

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The Four Parts of Medicare — How They Fit Together

Medicare is divided into four distinct parts. Each part was created at a different time and covers a different type of health care expense. Here is how they work together:

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The Two Paths — Original Medicare or Medicare Advantage

Once you are enrolled in Medicare, you have a fundamental choice to make about how you receive your benefits. This is one of the most important decisions in the entire Medicare process — and it shapes everything else about your coverage, your costs, and your access to care.

Path 1 — Original Medicare (Parts A and B)

With Original Medicare, the federal government pays your health care claims directly. You can see any doctor or specialist in the country who accepts Medicare — no network restrictions, no referrals required. Medicare pays its share of each covered service, and you pay your share through deductibles, copays, and coinsurance.

The major limitation of Original Medicare is that it leaves gaps — specifically, the 20% coinsurance under Part B, which has no out-of-pocket maximum. To fill those gaps, most people on Original Medicare add a Medicare Supplement (Medigap) plan and a standalone Part D drug plan.

Path 2 — Medicare Advantage (Part C)

With Medicare Advantage, you receive all of your Medicare benefits through a private insurance company instead of directly from the government. The federal government pays that company a set amount each month to cover your care. In exchange, the plan manages your benefits, maintains a network of providers, and sets its own cost-sharing structure.

Medicare Advantage plans often include benefits Original Medicare does not cover — such as dental, vision, hearing, and fitness memberships. Many plans have $0 monthly premiums. However, you are generally limited to the plan’s network of doctors and hospitals, and you may need referrals to see specialists depending on the plan type.

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How Medicare Actually Pays Your Bills

One of the most confusing aspects of Medicare for new beneficiaries is understanding how the payment process actually works. Here is how it flows from the moment you receive care to the moment the bill is settled:

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What Medicare Covers — and What It Does Not

Medicare covers a wide range of medically necessary services — but it is not all-inclusive. Understanding the boundaries of your coverage helps you plan for the costs that Medicare will not pay.

What Medicare Typically Covers

• Inpatient hospital care — room, nursing, meals, and most hospital services during an admitted stay
• Doctor visits — both primary care and specialist appointments for medically necessary reasons
• Outpatient surgery and procedures
• Preventive care — annual wellness visits, many screenings, and vaccinations at no cost
• Lab work, X-rays, and diagnostic imaging
• Physical, occupational, and speech therapy
• Durable medical equipment — wheelchairs, walkers, CPAP machines, and similar devices
• Skilled nursing facility care — after a qualifying hospital stay of at least 3 days
• Home health care — when medically necessary and ordered by a doctor
• Hospice care — for beneficiaries with a terminal diagnosis
• Prescription drugs — through a Part D plan or Medicare Advantage with drug coverage

What Medicare Does NOT Cover

• Routine dental care — cleanings, fillings, extractions, and dentures
• Routine vision care — eye exams for glasses and contact lenses
• Hearing aids and routine hearing exams
• Long-term custodial care — help with daily living activities in a nursing home or at home
• Most care received outside the United States
• Cosmetic surgery
• Acupuncture (with limited exceptions)
• Private-duty nursing

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What Does Medicare Cost?

Medicare is not free — but for most people, it is significantly less expensive than private health insurance. Your costs depend on which parts of Medicare you have, what supplemental coverage you choose, and how much health care you actually use. Here is a quick overview of the main costs involved:

For a deeper look at exactly what Medicare costs in 2026 — including how IRMAA surcharges work and how to estimate your total annual out-of-pocket expenses — see our dedicated page: What Does Medicare Cost in 2026?

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How Do You Get Medicare?

Most people become eligible for Medicare at age 65. If you are already receiving Social Security benefits when you turn 65, you are typically enrolled in Parts A and B automatically — your Medicare card arrives in the mail about three months before your 65th birthday. If you are not yet collecting Social Security, you need to actively sign up for Medicare during your Initial Enrollment Period.

Your Initial Enrollment Period is a seven-month window — three months before your birthday month, your birthday month itself, and three months after. Enrolling during the first three months ensures your coverage starts the month you turn 65. Waiting until after your birthday month may delay your start date.

Missing your Initial Enrollment Period without having qualifying coverage through an employer can result in lifetime late enrollment penalties — a permanent increase in your Part B and Part D premiums that stays with you for as long as you have Medicare. This is one of the most important reasons to pay attention to your enrollment window.

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Your Next Steps With Medicare

Understanding how Medicare works is the foundation — but the decisions you make on top of that foundation determine how much you pay, how much flexibility you have, and how well your coverage actually meets your health care needs. Here are the decisions most people need to work through:

• When to enroll — and whether your current employer coverage qualifies as creditable coverage that lets you delay without penalty
• Original Medicare vs. Medicare Advantage — which path fits your doctors, your health needs, and your budget
• Whether to add a Medigap plan — and if so, which plan letter makes the most sense for your situation
• Which Part D plan to choose — based on your specific prescriptions and preferred pharmacy
• How Medicare interacts with any other coverage you currently have — such as a spouse’s employer plan, VA benefits, or TRS coverage

None of these decisions has to be made alone. A licensed Medicare advisor in the Rio Grande Valley can walk you through each one — comparing your specific options, explaining the trade-offs clearly, and helping you choose the coverage that genuinely fits your life. The consultation is always free.