Medicare has only four main lettered parts, yet understanding them can feel like someone spilled alphabet soup across an insurance contract. Part A covers one category of care, Part B handles another, Part C rearranges the first two into a private plan, and Part D focuses on prescription drugs. Then Medigap wanders into the conversation without receiving its own letter. Naturally.
The system becomes much easier once you understand that Medicare offers two main coverage paths. You can use Original Medicare, which consists of Part A and Part B, and add separate drug and supplemental coverage. Alternatively, you can receive most Medicare benefits through a private Medicare Advantage plan, also called Part C. Medicare generally covers people age 65 and older, along with certain younger people who have qualifying disabilities or medical conditions.
Important: The dollar amounts in this guide reflect 2026 Medicare costs. Premiums, deductibles, plan networks, formularies, and benefits can change every year.
The Four Parts of Medicare at a Glance
| Medicare Part | Main Purpose | How It Is Provided | Major Detail to Remember |
|---|---|---|---|
| Part A | Hospital and inpatient coverage | Federal government | Most people receive premium-free Part A |
| Part B | Medical and outpatient coverage | Federal government | Usually requires a monthly premium |
| Part C | Private alternative to Original Medicare | Medicare-approved private insurers | Combines Parts A and B and usually Part D |
| Part D | Prescription drug coverage | Medicare-approved private insurers | Drug lists, pharmacies, and costs vary by plan |
Parts A and B make up Original Medicare. Part C, or Medicare Advantage, is an alternative way to receive Part A and Part B benefits. Part D may be purchased as a stand-alone plan with Original Medicare and is usually built into Medicare Advantage plans.
Medicare Part A: Hospital Insurance
Medicare Part A is commonly described as hospital insurance. That description is accurate, although Part A covers more than a hospital room and the world’s least fashionable open-back gown.
What Does Medicare Part A Cover?
Part A helps cover medically necessary inpatient hospital care, inpatient rehabilitation, care in critical access hospitals, qualifying skilled nursing facility care, hospice services, and certain home health services. Coverage depends on Medicare rules, medical necessity, and whether the facility or provider participates in Medicare.
Skilled nursing facility coverage is not the same as unlimited nursing-home coverage. It is designed for qualifying short-term skilled care, such as rehabilitation or nursing services following an eligible hospital stay. Part A generally does not pay for long-term custodial care when a person mainly needs assistance with activities such as bathing, eating, or dressing.
What Does Part A Cost in 2026?
Most beneficiaries pay no monthly Part A premium because they or a spouse worked and paid Medicare taxes long enough, generally for at least 40 calendar quarters. People who must purchase Part A pay either $311 or $565 per month in 2026, depending on their work history.
Premium-free does not mean cost-free. In 2026, Original Medicare charges a $1,736 Part A deductible for each inpatient hospital benefit period. Unlike a typical annual deductible, this amount can potentially apply more than once during the same year if separate benefit periods occur.
After the deductible, beneficiaries pay no hospital coinsurance for days 1 through 60 of a covered benefit period. The 2026 coinsurance is $434 per day for days 61 through 90 and $868 per lifetime reserve day for days 91 through 150. Covered skilled nursing facility care costs $0 for days 1 through 20 and $217 per day for days 21 through 100.
What Part A Usually Does Not Cover
Part A generally does not cover private-duty nursing, private hospital rooms unless medically necessary, routine personal care, most long-term custodial care, or every service provided during a hospital stay. For example, doctors who treat an inpatient usually bill their professional services through Part B rather than Part A.
Medicare Part B: Medical Insurance
If Part A covers the bed upstairs in the hospital, Part B covers many of the people, tests, supplies, and outpatient services surrounding that bed.
What Does Medicare Part B Cover?
Part B helps cover physician services, outpatient hospital care, preventive services, diagnostic testing, ambulance transportation, mental health treatment, durable medical equipment, certain home health services, clinical research, oxygen equipment, and a limited category of outpatient drugs.
Examples include primary care appointments, specialist visits, outpatient surgery, physical therapy, wheelchairs, walkers, diabetes supplies, flu shots, cancer screenings, and an annual wellness visit when Medicare requirements are met.
What Does Part B Cost in 2026?
The standard Part B premium is $202.90 per month in 2026, and the annual deductible is $283. After the deductible, beneficiaries generally pay 20% of the Medicare-approved amount for covered Part B services when the provider accepts Medicare assignment. Certain preventive and laboratory services may have no cost sharing.
People with higher modified adjusted gross income may pay an income-related monthly adjustment amount, commonly called IRMAA, in addition to their normal Part B premium. The Social Security Administration generally calculates 2026 IRMAA using income reported on a 2024 federal tax return. Higher-income beneficiaries may also pay an IRMAA surcharge for Part D.
Can You Delay Part B?
Some people can delay Part B without a penalty while covered by a qualifying group health plan based on their own or a spouse’s current employment. COBRA, retiree coverage, Marketplace insurance, individual coverage, and Veterans Affairs benefits do not automatically provide the same Part B Special Enrollment Period protections.
When no valid enrollment exception applies, the Part B late enrollment penalty is generally an additional 10% of the standard premium for each complete 12-month period a person could have had Part B but did not enroll. In many cases, the increased premium continues for as long as the person has Part B.
Medicare Part C: Medicare Advantage
Medicare Part C is better known as Medicare Advantage. It is not an extra layer placed on top of Original Medicare. Instead, it is an alternative way to receive Medicare-covered services through a private insurance company approved by Medicare.
How Medicare Advantage Works
To join a Medicare Advantage plan, you generally need both Part A and Part B and must live in the plan’s service area. You remain enrolled in Medicare and continue paying the Part B premium. The private plan becomes responsible for administering your Part A and Part B benefits. Most plans also include Part D prescription drug coverage.
Medicare Advantage plans must cover the medically necessary services covered by Original Medicare, but they may use different deductibles, copayments, provider networks, referrals, and prior authorization requirements. Many also advertise supplemental benefits such as routine dental, vision, hearing, fitness, transportation, or over-the-counter allowances. Benefits differ significantly by plan and location.
Medicare Advantage Advantages
- Part A, Part B, and usually Part D are bundled into one plan.
- Many plans charge no additional premium beyond the Part B premium.
- Plans have an annual out-of-pocket limit for covered Part A and Part B services.
- Additional dental, vision, hearing, or wellness benefits may be included.
- Coordinated provider networks may simplify care for some members.
In 2026, 75% of people enrolled in individual Medicare Advantage plans with drug coverage pay no additional plan premium beyond their Part B premium. However, a zero-dollar premium does not mean zero-dollar health care. Copayments, coinsurance, deductibles, out-of-network charges, and drug expenses may still apply.
Medicare Advantage Trade-Offs
Original Medicare lets beneficiaries visit any provider in the United States who accepts Medicare. Medicare Advantage members may need to use an HMO or PPO network, obtain specialist referrals, or receive prior authorization before selected services are covered. PPO plans may cover out-of-network care at a higher cost, while many HMOs generally do not cover routine out-of-network services.
Provider participation can also change. Before choosing a plan, verify that your physicians, preferred hospital, pharmacy, medical equipment suppliers, and prescription drugs are covered. Do not rely only on a glossy brochure featuring two unusually cheerful retirees riding bicycles beside a lake.
Medicare Part D: Prescription Drug Coverage
Medicare Part D helps pay for covered brand-name and generic prescription drugs. It is optional, but delaying enrollment without other creditable drug coverage can trigger a late enrollment penalty. Private insurers provide Part D through stand-alone prescription drug plans and Medicare Advantage plans that include drug coverage.
How Part D Plans Cover Medications
Each plan maintains a formulary, or list of covered drugs. Medications are commonly grouped into cost-sharing tiers. A generic drug may have a small copayment, while a preferred brand, nonpreferred drug, or specialty medication may cost considerably more.
Plans may also use prior authorization, quantity limits, or step therapy. Pharmacy networks matter as well: filling the same prescription at a preferred pharmacy may cost less than using another in-network pharmacy. Therefore, comparing premiums alone is a reliable way to choose the wrong plan with great confidence.
Part D Costs in 2026
Part D premiums and cost sharing vary by plan. The maximum standard deductible is $615 in 2026, although plans may charge a smaller deductible or no deductible. Once a beneficiary’s qualifying out-of-pocket spending on covered Part D drugs reaches $2,100 in 2026, the beneficiary pays no additional out-of-pocket amount for covered Part D medications for the remainder of the calendar year.
To avoid a Part D late enrollment penalty, beneficiaries generally should not go 63 consecutive days or longer without Part D or other creditable prescription coverage after becoming eligible. The penalty is usually added to the monthly premium and may continue as long as the person has Part D.
People with limited income and financial resources may qualify for the Extra Help program, which can reduce Part D premiums, deductibles, and copayments. Applications can be submitted through the Social Security Administration before or after enrolling in Part D.
How the Medicare Parts Fit Together
Option One: Original Medicare
A common Original Medicare package includes:
- Part A for hospital coverage
- Part B for medical and outpatient coverage
- A stand-alone Part D plan for prescription drugs
- An optional Medigap policy to reduce certain out-of-pocket expenses
Original Medicare offers broad nationwide provider access, but it has no annual limit on a beneficiary’s Part A and Part B out-of-pocket spending. A Medigap policy can help pay certain deductibles, copayments, and coinsurance amounts. Medigap works only with Original Medicare and cannot be used to pay Medicare Advantage cost sharing.
Option Two: Medicare Advantage
A Medicare Advantage package usually includes:
- Part A benefits
- Part B benefits
- Part D prescription coverage
- Possible supplemental benefits
- A defined annual out-of-pocket limit for covered Part A and Part B services
Medicare Advantage may appeal to people who prefer bundled coverage and predictable copayments. Original Medicare may appeal to people who prioritize nationwide provider choice, fewer network restrictions, or the ability to pair Medicare with Medigap.
Important Medicare Enrollment Periods
Initial Enrollment Period
For many people who become eligible at age 65, the Initial Enrollment Period lasts seven months: the three months before the birthday month, the birthday month, and the three months after it. Enrollment timing can affect when coverage begins.
General Enrollment Period
People who miss their initial opportunity and do not qualify for a Special Enrollment Period may enroll in Part A, when a premium is required, and Part B from January 1 through March 31. Coverage generally begins the month after enrollment, and late penalties may apply.
Annual Medicare Open Enrollment
From October 15 through December 7, beneficiaries may switch Medicare Advantage plans, move between Original Medicare and Medicare Advantage, or join, drop, or change a Part D plan. Changes generally take effect January 1.
Medicare Advantage Open Enrollment
From January 1 through March 31, people already enrolled in Medicare Advantage may make one change to another Medicare Advantage plan or return to Original Medicare and join a stand-alone drug plan. This period cannot be used by someone in Original Medicare to join Medicare Advantage.
How to Choose the Right Medicare Combination
There is no universally “best” Medicare option. The correct choice depends on health conditions, prescriptions, location, travel habits, preferred providers, financial resources, and tolerance for insurance paperwork.
Ask These Questions Before Enrolling
- Do my doctors accept the coverage? Check every important physician, hospital, specialist, and facility.
- Are my prescriptions covered? Review the exact drug name, dosage, tier, restrictions, and preferred pharmacies.
- What could I pay in a difficult health year? Add premiums, deductibles, copayments, coinsurance, and the plan’s out-of-pocket limit.
- Do I travel or live in more than one state? Nationwide access may matter more than attractive local extras.
- Could I obtain Medigap later? In many states, switching from Medicare Advantage to Original Medicare later may involve medical underwriting unless a guaranteed-issue right applies.
Plan benefits and networks can change annually, so beneficiaries should review the Annual Notice of Change rather than allowing coverage to renew on autopilot. Free, unbiased, one-on-one Medicare counseling is available through State Health Insurance Assistance Programs, commonly known as SHIP.
Common Real-World Experiences With Medicare Parts
The following examples are illustrative composites based on situations commonly encountered by Medicare beneficiaries. They show why matching coverage to a person’s actual life matters more than selecting a plan because its television commercial contains a celebrity, a toll-free number, and an impressive amount of smiling.
Experience One: The Traveler Who Chose a Local Network
Consider a retired couple who spends six months at home and several months visiting children in other states. They choose a low-premium Medicare Advantage HMO because their local doctors participate and the plan includes dental and vision benefits. The plan works well at home. During an extended trip, however, one spouse needs nonemergency specialist care. Emergency services are covered, but routine treatment outside the plan’s service area is difficult to arrange.
The lesson is not that Medicare Advantage is bad. The lesson is that provider geography matters. A local network can be perfectly suitable for someone who rarely travels and frustrating for someone who regularly receives care in several states. Original Medicare may provide greater flexibility for frequent travelers because it can be used with participating providers throughout the country.
Experience Two: The Healthy Retiree Who Skipped Part D
Another beneficiary takes no regular medications at age 65 and decides that Part D would be an unnecessary expense. Several years later, a new diagnosis requires multiple prescriptions. The beneficiary enrolls during an available enrollment period but discovers that a permanent late enrollment penalty has been added because there was no creditable drug coverage during the gap.
A low-premium Part D plan might have cost money during the healthy years, but it would also have provided insurance against future prescriptions and protected against the penalty. Drug coverage is not merely a discount program for medications someone already takes. Like most insurance, it is purchased partly for the health problems nobody has scheduled yet.
Experience Three: The Zero-Premium Plan That Was Not Free
A beneficiary selects a zero-premium Medicare Advantage plan and reasonably assumes monthly health costs will be minimal. Routine primary care is inexpensive, and the included dental allowance seems valuable. Later, imaging, outpatient therapy, specialist visits, and a hospital stay produce multiple copayments.
The plan did not malfunction. “Zero premium” simply meant the insurer charged no additional monthly plan premium beyond the required Part B premium. It did not eliminate deductibles or cost sharing. This experience highlights why shoppers should compare estimated annual costs under both routine and high-use scenarios rather than focusing exclusively on the premium.
Experience Four: The Prescription List That Changed the Winner
A married couple initially plans to enroll in the same Part D plan because sharing an insurer seems convenient. When they enter their prescriptions into a plan comparison tool, the results are dramatically different. One spouse’s medications are inexpensive under Plan A, while the other spouse’s drugs are assigned to higher tiers and require a less convenient pharmacy. Plan B is better for the second spouse.
The couple chooses different Part D plans. Their mail is slightly less tidy, but their projected prescription spending is much lower. Medicare is individual coverage, and spouses do not have to choose matching plans. Convenience is useful, but it should not be purchased with hundreds or thousands of dollars in avoidable drug costs.
Experience Five: The Retiree Who Assumed COBRA Protected Part B Enrollment
One of the most expensive Medicare mistakes occurs when someone leaves a job, elects COBRA, and assumes the coverage allows Part B enrollment to be postponed indefinitely. Medicare rules generally treat active-employment coverage differently from COBRA. Missing the applicable Part B enrollment window can create a coverage gap and a long-term penalty.
Before retiring, workers should ask the employer’s benefits department how the group plan coordinates with Medicare and confirm the answer with Social Security, Medicare, or a SHIP counselor. A ten-minute verification may prevent months without primary coverage and years of higher premiums.
Conclusion
Medicare becomes manageable when each letter receives a clear job. Part A covers inpatient and hospital-related care. Part B covers physicians, outpatient services, medical equipment, and preventive care. Part C delivers Part A and Part B benefits through a private Medicare Advantage plan and usually includes Part D. Part D covers prescription medications.
The larger decision is whether to choose Original Medicare with optional Part D and Medigap coverage or enroll in a Medicare Advantage plan. Compare total costs, provider access, prescription coverage, travel needs, plan rules, and financial assistance programs. Review coverage every year, because the plan that fits today may fit next year about as well as an old pair of orthopedic shoes.
Editorial note: This article provides general educational information and does not replace personalized guidance from Medicare, Social Security, a licensed insurance professional, an employer benefits administrator, or a SHIP counselor. Coverage and costs should be verified for the beneficiary’s location and enrollment year.
