Understanding the four parts of Medicare is the first step toward making confident healthcare decisions in retirement. Each part covers different services, has its own costs, and works together to form a comprehensive health insurance framework for Americans 65 and older.
This 2026 guide breaks down Medicare Part A, Part B, Part C (Medicare Advantage), and Part D so you can see exactly what each part covers, what it costs, and how to choose the right combination for your needs.
What Are the 4 Parts of Medicare?
Medicare is divided into four distinct parts, each designed to cover specific types of healthcare services:
- Part A — Hospital Insurance
- Part B — Medical Insurance
- Part C — Medicare Advantage (private plan alternative)
- Part D — Prescription Drug Coverage
Parts A and B together form Original Medicare, which is administered directly by the federal government. Parts C and D are offered through private insurance companies approved by Medicare. Most beneficiaries combine these parts based on their healthcare needs, budget, and preferences.
Medicare Part A: Hospital Insurance
Medicare Part A covers inpatient hospital care and related services. If you need to be admitted to a hospital, receive skilled nursing care after a hospital stay, or use hospice services, Part A is the portion of Medicare that pays for it.
What Part A Covers
- Inpatient hospital stays (semi-private room, meals, nursing services, medications)
- Skilled nursing facility (SNF) care (days 1–100 following a qualifying 3-day hospital stay)
- Home health services (part-time skilled nursing, physical therapy, occupational therapy)
- Hospice care (pain management, symptom relief, counseling for terminal illness)
- Inpatient care at religious non-medical healthcare institutions
Part A Costs in 2026
Most people pay $0 per month for Part A because they (or a spouse) paid Medicare payroll taxes for at least 40 quarters (10 years of work). However, Part A still includes deductibles and coinsurance for hospital stays:
| Cost Component | 2026 Amount | Notes |
|---|---|---|
| Part A premium (40+ quarters) | $0/month | ~99% of enrollees qualify |
| Part A premium (30–39 quarters) | $311/month | Reduced buy-in premium |
| Part A premium (<30 quarters) | $565/month | Full buy-in premium |
| Inpatient hospital deductible | $1,736 per benefit period | Covers first 60 days |
| Hospital coinsurance (days 61–90) | $434/day | Per benefit period |
| Lifetime reserve days (days 91–150) | $868/day | 60 lifetime reserve days total |
| Skilled nursing facility (days 21–100) | $217/day | Days 1–20 are $0 |
Source: CMS MM14279 — CY 2026 Medicare Rates
A benefit period begins when you are admitted to a hospital and ends 60 consecutive days after your discharge. If you are readmitted after a benefit period ends, a new deductible applies. This is one of the key Medicare costs that catches people off guard.
Medicare Part B: Medical Insurance
Medicare Part B covers outpatient medical services, which includes most of the healthcare you receive outside of a hospital. Doctor visits, lab tests, preventive screenings, and durable medical equipment all fall under Part B.
What Part B Covers
- Doctor and specialist visits
- Outpatient hospital services and surgeries
- Preventive services (annual wellness visits, flu shots, cancer screenings, cardiovascular tests)
- Durable medical equipment (wheelchairs, walkers, hospital beds, oxygen equipment)
- Mental health services (outpatient therapy, partial hospitalization)
- Ambulance services
- Some home health services
- Clinical lab tests and diagnostic imaging
Part B Costs in 2026
Unlike Part A, nearly every Medicare beneficiary pays a monthly premium for Part B. In 2026:
- Standard monthly premium: $202.90
- Annual deductible: $283
- Coinsurance: 20% of the Medicare-approved amount after the deductible
After meeting the $283 deductible, Medicare pays 80% and you pay 20% of covered services with no annual out-of-pocket maximum under Original Medicare. This unlimited cost exposure is one of the main reasons many beneficiaries add Medigap (Medicare Supplement) coverage.
Part B IRMAA: Income-Related Surcharges
Higher-income beneficiaries pay more for Part B through the Income-Related Monthly Adjustment Amount (IRMAA). Medicare uses your tax return from two years prior (2024 income for 2026 premiums) to determine your surcharge:
| Individual Income (2024) | Joint Income (2024) | 2026 Monthly Premium |
|---|---|---|
| ≤ $109,000 | ≤ $218,000 | $202.90 (standard) |
| $109,001 – $137,000 | $218,001 – $274,000 | $284.00 |
| $137,001 – $171,000 | $274,001 – $342,000 | $405.80 |
| $171,001 – $214,000 | $342,001 – $428,000 | $527.50 |
| $214,001 – $500,000 | $428,001 – $750,000 | $649.30 |
| ≥ $500,000 | ≥ $750,000 | $689.90 |
For a deeper breakdown of all costs, see our 2026 Medicare premiums and costs guide.
Medicare Part C: Medicare Advantage
Medicare Part C, commonly called Medicare Advantage, is an alternative way to receive your Medicare benefits. Instead of getting Part A and Part B directly from the government, you enroll in a private insurance plan that is approved by Medicare and provides at least the same level of coverage.
How Medicare Advantage Works
- Bundles Part A, Part B, and usually Part D into a single plan
- Offered by private insurance companies (UnitedHealthcare, Humana, Aetna, etc.)
- You must still pay your Part B premium ($202.90/month) in addition to any plan premium
- Many plans charge $0 in additional premiums
- Includes an annual out-of-pocket maximum (capped at $9,250 in 2026), which Original Medicare does not have
Extra Benefits
Many Medicare Advantage plans include benefits that Original Medicare does not cover:
- Dental coverage (cleanings, fillings, dentures)
- Vision coverage (eye exams, glasses, contacts)
- Hearing coverage (hearing exams, hearing aids)
- Fitness programs (gym memberships like SilverSneakers)
- Transportation to medical appointments
- Over-the-counter medication allowances
Trade-Offs to Consider
Medicare Advantage plans typically use provider networks (HMO or PPO), which means you may need to use specific doctors and hospitals. Referrals may be required for specialists with HMO plans. You also cannot use a Medigap policy alongside Medicare Advantage.
To understand the full picture of how these plans compare, read our Medicare Advantage vs. Medigap comparison.
Medicare Part D: Prescription Drug Coverage
Medicare Part D provides coverage for outpatient prescription drugs through private insurance plans approved by Medicare. You can get Part D as a stand-alone plan (paired with Original Medicare) or as part of a Medicare Advantage plan that includes drug coverage (MA-PD).
What Part D Covers
- Brand-name and generic prescription medications
- Many recommended vaccines and immunizations
- Insulin (capped at $35/month under the Inflation Reduction Act)
- Medications on the plan’s formulary (drug list)
Each Part D plan has a formulary, which is a list of covered drugs organized into cost tiers. Before enrolling in any plan, check that your medications are on the formulary at an affordable tier.
Part D Costs in 2026
- National base premium: approximately $38.99/month (actual plan premiums vary)
- Maximum annual deductible: $615 (some plans have lower or no deductible)
- Annual out-of-pocket cap: $2,100
The $2,100 Out-of-Pocket Cap (New for 2025–2026)
One of the most significant Medicare changes in recent years: thanks to the Inflation Reduction Act, Part D now includes a hard annual cap on out-of-pocket drug costs. Once you spend $2,100 on covered Part D medications in 2026, you pay $0 for the rest of the calendar year.
This cap replaced the old “donut hole” coverage gap that previously left beneficiaries paying full price for medications during a middle spending phase. The donut hole is now fully eliminated. For more on how this works, see our complete Part D guide.
Part D also benefits from Medicare drug price negotiations — in 2026, the first 10 negotiated drug prices went into effect, saving an estimated $1.5 billion for 8.8 million beneficiaries on common medications for heart disease, diabetes, arthritis, and cancer.
How the 4 Parts of Medicare Work Together
The four parts of Medicare are not entirely separate; they work in combination. Here is how most beneficiaries structure their coverage:
Option 1: Original Medicare + Medigap + Part D
- Part A (hospital) + Part B (medical) = Original Medicare
- Add a Medigap policy (such as Plan G) to cover deductibles and the 20% coinsurance gap
- Add a stand-alone Part D plan for prescription drug coverage
- Pros: See any doctor who accepts Medicare nationwide, predictable costs with Medigap
- Cons: Higher monthly premiums, no extra benefits (dental, vision, hearing)
Option 2: Medicare Advantage (Part C) with Part D
- One plan replaces Parts A, B, and usually includes Part D
- Pros: Lower premiums (often $0), extra benefits, annual out-of-pocket cap
- Cons: Network restrictions, may need referrals, limited to plan service area
Your ideal choice depends on your health needs, budget, preferred doctors, travel plans, and tolerance for cost uncertainty. Beneficiaries who want maximum flexibility and predictability often choose Original Medicare with a Medigap supplement. Those who want lower premiums and extra benefits may prefer Medicare Advantage.
Comparison Table: All 4 Parts of Medicare at a Glance (2026)
| Feature | Part A (Hospital) | Part B (Medical) | Part C (Medicare Advantage) | Part D (Drugs) |
|---|---|---|---|---|
| What It Covers | Inpatient hospital, SNF, hospice, home health | Doctor visits, outpatient, preventive care, DME | Everything in A & B, often includes D plus extras | Prescription medications, vaccines, insulin |
| Monthly Premium | $0 for most (up to $565) | $202.90 standard | $0–varies (+ $202.90 Part B premium) | ~$38.99 base (varies by plan) |
| Annual Deductible | $1,736 per benefit period | $283/year | Varies by plan | Up to $615 |
| Out-of-Pocket Max | None | None | $9,250 (2026 cap) | $2,100 |
| Provider Network | Any Medicare-accepting provider | Any Medicare-accepting provider | Plan network (HMO/PPO) | Plan pharmacy network |
| Enrollment | Automatic at 65 if receiving Social Security | Automatic at 65 if receiving Social Security | Annual Enrollment Period (Oct 15 – Dec 7) | Annual Enrollment Period (Oct 15 – Dec 7) |
| Run By | Federal government | Federal government | Private insurers (Medicare-approved) | Private insurers (Medicare-approved) |
Medigap: Supplementing Original Medicare
If you choose Original Medicare (Parts A and B), you may want to add a Medicare Supplement (Medigap) policy. Medigap fills the “gaps” in Original Medicare, covering costs like the Part A deductible, Part B coinsurance, and excess charges.
Medigap policies are standardized by the federal government and labeled by letters (Plan A, Plan B, Plan G, Plan N, etc.). The two most popular plans in 2026 are:
- Plan G: Covers everything except the Part B deductible ($283 in 2026). Most comprehensive option available to new enrollees.
- Plan N: Similar to Plan G but with small copays at doctor visits ($20) and ER ($50). Lower premiums than Plan G.
Important: You cannot use a Medigap policy with Medicare Advantage. Medigap only works with Original Medicare (Parts A and B).
When to Enroll in Each Part of Medicare
Medicare enrollment timing matters. Missing your window can result in late enrollment penalties that increase your premiums permanently.
- Parts A & B: Your Initial Enrollment Period (IEP) is the 7-month window around your 65th birthday (3 months before, your birthday month, and 3 months after). If you are already receiving Social Security, you may be auto-enrolled.
- Part C (Medicare Advantage): Enroll during your IEP, the Annual Enrollment Period (Oct 15 – Dec 7), or the Medicare Advantage Open Enrollment Period (Jan 1 – Mar 31).
- Part D: Enroll during your IEP or the Annual Enrollment Period. If you delay without creditable drug coverage, a late enrollment penalty of 1% per month applies permanently.
- Medigap: Your Medigap Open Enrollment Period starts the month you turn 65 AND are enrolled in Part B. During this 6-month window, insurance companies cannot deny you coverage or charge more due to pre-existing conditions.
Frequently Asked Questions About the Parts of Medicare
Is Medicare Part C the same as Medicare Advantage?
Yes. Medicare Part C is the official name for Medicare Advantage. These are private insurance plans approved by Medicare that bundle Part A, Part B, and usually Part D into a single plan, often with additional benefits like dental, vision, and hearing coverage.
Do I need all 4 parts of Medicare?
Not necessarily. Almost everyone enrolls in Part A (it is premium-free for most) and Part B. From there, you choose either a Medicare Advantage plan (Part C, which typically includes Part D) or you stay on Original Medicare and add a stand-alone Part D plan. You do not enroll in all four parts simultaneously.
What is the difference between Original Medicare and Medicare Advantage?
Original Medicare (Parts A + B) is run by the federal government. You can see any doctor or hospital that accepts Medicare, anywhere in the U.S. Medicare Advantage (Part C) is run by private insurance companies, often has lower premiums and extra benefits, but uses provider networks that may limit your choice of doctors.
Can I switch between Original Medicare and Medicare Advantage?
Yes. During the Annual Enrollment Period (October 15 – December 7), you can switch from Original Medicare to Medicare Advantage or vice versa. During the Medicare Advantage Open Enrollment Period (January 1 – March 31), Medicare Advantage enrollees can switch to a different MA plan or return to Original Medicare.
How much does Medicare cost per month in 2026?
For most beneficiaries on Original Medicare: $0 for Part A + $202.90 for Part B + approximately $34–$40 for Part D = roughly $237–$243 per month before Medigap premiums. Medicare Advantage enrollees pay their Part B premium ($202.90) plus a plan premium (often $0). Higher-income beneficiaries may pay IRMAA surcharges on both Part B and Part D. See our full 2026 Medicare costs breakdown.
What is IRMAA and does it affect all parts of Medicare?
IRMAA (Income-Related Monthly Adjustment Amount) is a surcharge added to Part B and Part D premiums for higher-income beneficiaries. It is based on your modified adjusted gross income from two years prior. In 2026, IRMAA applies if your individual income exceeds $109,000 or joint income exceeds $218,000.
Does Medicare cover dental, vision, and hearing?
Original Medicare (Parts A and B) provides very limited dental, vision, and hearing coverage. However, many Medicare Advantage (Part C) plans include dental, vision, and hearing benefits as part of their plan.
When is the best time to enroll in Medicare?
The best time is during your Initial Enrollment Period, which starts 3 months before you turn 65 and ends 3 months after your birthday month. Enrolling during this 7-month window avoids late penalties and ensures seamless coverage. Read our complete enrollment guide for step-by-step instructions.