Difference Between

Difference Between Medicare Part a and B

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Quick answer

The main difference between Medicare Part a and B is that Medicare Part a covers inpatient hospital care, skilled nursing facilities, and hospice, while B covers outpatient services like doctor visits and preventive care. Medicare Part a is hospital insurance, while B is medical insurance.

Key takeaways

  • Core distinction: Part A covers hospital inpatient care, while Part B covers outpatient medical services.
  • How each works: Part A pays for hospital stays, skilled nursing, and hospice; Part B covers doctor visits.
  • Cost difference: Part A is usually premium-free for most workers, but Part B has a monthly premium.
  • Best-fit use case: Choose Part A for surgeries or hospitalizations, and Part B for preventive care appointments.
  • Common mistake: Many people skip Part B to save money, then face late enrollment penalties.

Difference Between Medicare Part a and B: Comparison Table

AspectMedicare Part aB
DefinitionHospital insurance covering inpatient stays, skilled nursing, hospice, and some home health care.Medical insurance covering doctor visits, outpatient care, preventive services, and durable medical equipment.
Core PurposePays for care received while admitted as an inpatient in a hospital or skilled nursing facility.Pays for medically necessary services received outside a hospital, including lab tests and specialist consultations.
Coverage TriggerBegins only after a doctor orders formal inpatient admission and you stay at least two midnights.Begins with any covered outpatient service, including a single office visit or a blood test.
Premium CostMost enrollees pay $0 monthly because they or a spouse paid Medicare taxes for 40+ quarters.Most enrollees pay a standard monthly premium of $174.70 in 2024, adjusted by income.
DeductibleCharges a $1,632 per benefit period deductible in 2024, not an annual deductible.Charges a $240 annual deductible in 2024, which resets every January.
Cost SharingRequires no coinsurance for days 1-60, then $408 per day for days 61-90 in 2024.Requires a 20% coinsurance on most covered services after you meet the annual deductible.
Enrollment TimingAutomatic at age 65 if you already receive Social Security or Railroad Retirement Board benefits.Requires active enrollment during your 7-month Initial Enrollment Period unless you have qualifying coverage.
Penalty RiskNo late-enrollment penalty exists for Part a if you are eligible for premium-free coverage.Adds a 10% surcharge to your Part B premium for each 12-month period you delay enrollment.
Covered ServicesCovers inpatient hospital rooms, meals, nursing care, operating room costs, and hospice services.Covers doctor fees, outpatient surgery, X-rays, lab work, ambulance transport, and mental health services.
Excluded ServicesDoes not cover outpatient prescriptions, routine dental, vision exams, or hearing aids.Does not cover most prescription drugs, long-term custodial care, or routine foot care.
Benefit PeriodUses a benefit period that starts at admission and ends after 60 consecutive days without inpatient care.Operates on a calendar year basis, with your deductible and out-of-pocket costs resetting each January.
Lifetime ReserveOffers 60 lifetime reserve days that cover inpatient care beyond 90 days in a single benefit period.Has no lifetime day limits; you receive coverage indefinitely as long as you pay premiums and meet deductibles.
Skilled NursingCovers up to 100 days per benefit period in a skilled nursing facility after a 3-day inpatient stay.Does not cover skilled nursing facility stays, but pays for medically necessary therapy services in outpatient settings.
Home Health CareCovers part-time skilled nursing care and home health aide services when you are homebound.Covers physical, occupational, and speech therapy, plus durable medical equipment ordered by a doctor.
Hospice CareProvides full coverage for hospice care, including pain medication, grief counseling, and respite care.Does not cover hospice services; those fall exclusively under Part a for terminally ill beneficiaries.
Blood CoverageCovers the first 3 pints of blood you receive during an inpatient stay each calendar year.Covers blood received as an outpatient, but you pay a 20% coinsurance after the first 3 pints.
Durable EquipmentDoes not cover durable medical equipment like wheelchairs, walkers, or hospital beds.Covers durable medical equipment at 80% after you meet the annual deductible.
Preventive CareProvides no preventive screening services, such as mammograms, colonoscopies, or annual wellness visits.Covers 100% of many preventive services, including flu shots, cancer screenings, and the Welcome to Medicare visit.
Outpatient SurgeryDoes not cover same-day surgical procedures performed in an outpatient surgery center or clinic.Covers outpatient surgery, including facility fees and surgeon charges, subject to the 20% coinsurance.
Ambulance TransportCovers emergency ambulance transport only when inpatient admission is required and other transport is unsafe.Covers both emergency and non-emergency ambulance transport when medically necessary and documented.
Mental HealthCovers inpatient psychiatric hospital care with a 190-day lifetime limit for psychiatric stays.Covers outpatient mental health services, including therapy, at the standard 20% coinsurance rate.
Clinical TrialsCovers routine inpatient costs associated with qualifying clinical research studies.Covers routine outpatient costs and some testing associated with Medicare-approved clinical trials.
Geographic PortabilityProvides coverage throughout the United States and its territories, with no network restrictions.Provides nationwide coverage, but some services require prior authorization or specific supplier enrollment.
Supplement CompatibilityPairs with Medigap policies that cover your Part a coinsurance and extend skilled nursing coverage beyond 100 days.Pairs with Medigap policies that cover the 20% coinsurance and the annual Part B deductible.
Income AdjustmentDoes not charge higher premiums based on your income level when you qualify for premium-free Part a.Charges an Income-Related Monthly Adjustment Amount that raises premiums for individuals earning over $103,000.
Typical EnrolleeFits retirees who need protection against catastrophic hospital bills from surgeries, serious illness, or injury.Fits anyone who needs routine doctor care, diagnostic testing, or preventive screening on an ongoing basis.
Claim ProcessingProcesses claims through Medicare Administrative Contractors that pay hospitals directly for covered inpatient services.Processes claims through the same contractors, but you receive a Medicare Summary Notice detailing each service.
Coverage GapLeaves you responsible for all costs after day 90 unless you use lifetime reserve days or have Medigap.Has no catastrophic cap on your 20% coinsurance, so out-of-pocket costs can grow without limit.
Prescription DrugsDoes not cover outpatient prescription drugs, including medications you take after hospital discharge.Covers only a limited set of drugs administered in a doctor's office, such as chemotherapy or injections.
Best-Fit ScenarioBest for a planned surgical admission where you need a private room, nursing care, and inpatient monitoring.Best for managing chronic conditions like diabetes or hypertension that require frequent doctor visits and lab work.

What Is Medicare Part a?

Medicare Part a is the hospital insurance portion of the federal Medicare program. It covers inpatient hospital stays, skilled nursing facility care, hospice care, and some home health care. Part a exists to protect older Americans from catastrophic medical costs.

Definition of Medicare Part a

Medicare Part a is a federally administered health insurance benefit that pays for medically necessary inpatient hospital services, skilled nursing facility care following a qualifying hospital stay, hospice care for terminal illness, and limited home health services, funded primarily through payroll taxes.

Key Characteristics of Medicare Part a

CharacteristicWhat It Means in Practice
Premium-freeMost beneficiaries pay no monthly premium because they paid Medicare taxes while working.
Inpatient focusCovers care received as a registered inpatient, not outpatient or observation services.
Deductible appliesYou pay a deductible per benefit period before coverage begins, not per calendar year.
Benefit periodsA new benefit period starts after 60 days without inpatient hospital or skilled nursing care.
Skilled nursingCovers skilled nursing facility care only after a 3-day inpatient hospital stay.
Hospice coverageProvides comfort care for terminal patients with a life expectancy of six months or less.
Home healthCovers part-time skilled nursing and therapy at home, but not custodial care.
CoinsuranceYou pay daily coinsurance for hospital stays beyond 60 days in a benefit period.
Lifetime reserveOffers 60 extra hospital days over your lifetime after day 90 in a benefit period.
Tax fundedFinanced by a 2.9% payroll tax split between employees and employers.

Common Examples of Medicare Part a

  • Mayo Clinic inpatient admission – a hospital stay for surgery qualifies as covered inpatient care.
  • Hospice of the Valley – a terminal cancer patient receives comfort care covered by Part a.
  • Kindred skilled nursing facility – post-stroke rehabilitation after a qualifying 3-day hospital stay.
  • Johns Hopkins home health – part-time physical therapy at home after a hip replacement.
  • Cleveland Clinic heart surgery – a multi-day coronary bypass admission is covered inpatient care.
  • VITAS hospice care – end-of-life pain management for a patient with advanced heart failure.
  • Duke University Hospital – an overnight stay for pneumonia treatment qualifies as inpatient care.
  • Encompass Health rehab – intensive inpatient rehabilitation after a severe stroke.
  • Mass General emergency admission – an emergency room visit that leads to formal inpatient admission.
  • Home infusion therapy – skilled nursing visits to administer intravenous antibiotics at home.

Advantages and Limitations of Medicare Part a

AdvantagesLimitations
No monthly premium for most enrollees who paid payroll taxes for 10 years.Does not cover outpatient doctor visits, lab tests, or preventive screenings.
Covers expensive hospital stays that can otherwise cost tens of thousands of dollars.Charges a $1,632 deductible per benefit period, which can hit multiple times yearly.
Provides hospice care including grief counseling and respite for family caregivers.Skilled nursing coverage requires a prior 3-day inpatient hospital stay that many never have.
Includes some home health services without requiring prior hospitalization.Does not cover long-term custodial care in nursing homes or assisted living.
Offers 60 lifetime reserve days for extended hospitalizations beyond standard coverage.Daily coinsurance of $408 per day for days 61-90 quickly becomes financially burdensome.
Nationally standardized benefits across all 50 states.Excludes private hospital rooms, which are only covered when medically necessary.
Automatic enrollment at age 65 for most retirees receiving Social Security benefits.Observation status stays are not covered, leaving patients with surprise bills.
Works with Medigap or Medicare Advantage plans to reduce out-of-pocket costs.Does not cover prescription drugs, dental care, vision exams, or hearing aids.
No annual out-of-pocket maximum, unlike commercial insurance plans.Requires coinsurance for skilled nursing days 21-100, up to $204 per day.
Protects against catastrophic inpatient costs for seniors on fixed incomes.Does not cover emergency care received outside the United States or its territories.

What Is B?

Medicare Part B is the medical insurance half of Original Medicare. It covers doctor visits, outpatient care, preventive services, and medically necessary supplies. It exists to pay for services Part A does not cover, like physician fees and lab tests.

Definition of B

Medicare Part B is a federally administered fee-for-service health insurance program that pays for medically necessary physician services, outpatient hospital care, durable medical equipment, and preventive screenings. Beneficiaries pay a monthly premium, an annual deductible, and 20 percent coinsurance for most covered services.

Key Characteristics of B

CharacteristicWhat It Means in Practice
Monthly premiumYou pay a standard premium each month, which increases with higher income brackets.
Annual deductibleYou pay the full cost of covered services until you meet the yearly deductible amount.
20% coinsuranceAfter the deductible, you pay 20 percent of the Medicare-approved amount for most services.
Outpatient focusCovers care that does not require an overnight hospital stay, including clinic visits.
Preventive servicesMany screenings and annual wellness visits are covered at no cost to you.
No out-of-pocket capUnlike commercial plans, Part B has no annual limit on your spending.
Medically necessary ruleServices must be deemed medically necessary by Medicare to qualify for payment.
Durable medical equipmentPays for wheelchairs, walkers, and oxygen equipment prescribed by a doctor.
Enrollment timingSigning up during your Initial Enrollment Period avoids late enrollment penalties.
Optional coverageYou can delay Part B if you have creditable coverage through an employer.

Common Examples of B

  • Doctor office visits – a primary care checkup for a sore throat qualifies as covered outpatient care.
  • Outpatient surgery – a colonoscopy performed at an ambulatory surgical center is covered under Part B.
  • Preventive screenings – a mammogram or colorectal cancer screening is covered at no cost.
  • Durable medical equipment – a hospital-grade oxygen concentrator for home use qualifies for coverage.
  • Ambulance transport – an emergency ground ambulance ride to a hospital is covered when medically necessary.
  • Clinical laboratory tests – blood work ordered by a physician for diagnostic purposes is fully covered.
  • Mental health services – outpatient therapy sessions with a licensed psychiatrist or psychologist qualify.
  • Physical therapy – medically necessary rehabilitation sessions after knee replacement surgery are covered.
  • Chemotherapy infusion – outpatient cancer treatment administered in a clinic setting falls under Part B.
  • Second surgical opinion – a consultation with another surgeon to confirm a recommended procedure is covered.

Advantages and Limitations of B

AdvantagesLimitations
Broad coverage for outpatient care across most medical specialties nationwide.No annual out-of-pocket maximum means catastrophic costs are possible without supplemental coverage.
Preventive services like vaccines and screenings are free to beneficiaries.The 20 percent coinsurance on expensive procedures like chemotherapy can become financially burdensome.
You can see any doctor who accepts Medicare assignment without referrals.Does not cover prescription drugs taken at home, routine dental, vision, or hearing aids.
Coverage is portable across all US states and territories.Late enrollment triggers a permanent premium penalty of 10 percent per year delayed.
Durable medical equipment is covered at 80 percent after the deductible.Medicare-approved amounts are often lower than what doctors charge, leaving you with balance bills.
No prior authorization required for most physician services.Overseas medical care is generally not covered, leaving travelers unprotected abroad.
Annual wellness visit and depression screening are included at no cost.You must pay the Part B premium even if you rarely use medical services.
Beneficiaries can choose between Original Medicare and Medicare Advantage plans.Coverage excludes long-term custodial care in nursing homes or assisted living facilities.
Income-based premium subsidies exist for low-income beneficiaries through Medicaid.High-income earners pay surcharges called IRMAA on top of the standard premium.
Claims are processed quickly with clear Explanation of Benefits statements.You must meet the annual deductible before most services are covered, creating upfront costs.

Similarities Between Medicare Part a and B

Shared AspectHow Medicare Part a and B Are Alike
Federal ProgramMedicare Part a and Medicare Part b are both federally administered health insurance programs in the United States.
Eligibility AgeMedicare Part a and Medicare Part b both become available to most Americans when they turn 65 years old.
Citizenship RuleMedicare Part a and Medicare Part b both require applicants to be United States citizens or permanent legal residents.
Enrollment WindowMedicare Part a and Medicare Part b both use the same initial seven-month enrollment period around a birthday.
CMS OversightMedicare Part a and Medicare Part b are both regulated and overseen by the Centers for Medicare and Medicaid Services.
Card IssuanceMedicare Part a and Medicare Part b both appear on the same red, white, and blue Medicare card.
Original MedicareMedicare Part a and Medicare Part b together form what is officially known as Original Medicare coverage.
Provider AcceptanceMedicare Part a and Medicare Part b are both accepted by the vast majority of doctors and hospitals nationwide.
Claim FilingMedicare Part a and Medicare Part b both process claims through the same government claims-processing contractors.
Coverage StartMedicare Part a and Medicare Part b both typically begin coverage on the first day of the enrollment month.
No NetworksMedicare Part a and Medicare Part b both allow beneficiaries to use any participating provider without referrals.
Portable CoverageMedicare Part a and Medicare Part b both provide coverage that remains valid across all fifty states.
Pre-Existing CareMedicare Part a and Medicare Part b both cover beneficiaries with pre-existing medical conditions without penalty.
Medigap CompatibleMedicare Part a and Medicare Part b both work alongside Medigap supplemental insurance policies.
Part D PairingMedicare Part a and Medicare Part b both coordinate with separate Medicare Part d prescription drug plans.
Advantage OptionMedicare Part a and Medicare Part b both serve as the base coverage replaced by Medicare Advantage plans.
Deductible SystemMedicare Part a and Medicare Part b both require beneficiaries to meet an annual deductible before full benefits apply.
Coinsurance ModelMedicare Part a and Medicare Part b both use coinsurance where beneficiaries pay a percentage of approved costs.
Coverage AppealsMedicare Part a and Medicare Part b both offer beneficiaries a formal five-level appeals process for denied claims.
Preventive FocusMedicare Part a and Medicare Part b both emphasize preventive care to avoid more costly treatments later.
Hospice CoverageMedicare Part a and Medicare Part b both provide coverage for terminal illness hospice care services.
Home HealthMedicare Part a and Medicare Part b both cover medically necessary home health care services under certain conditions.
Doctor OrdersMedicare Part a and Medicare Part b both require a physician's order for most covered services and supplies.
Medically NecessaryMedicare Part a and Medicare Part b both only pay for services deemed medically necessary by Medicare standards.
Annual UpdatesMedicare Part a and Medicare Part b both have their costs and coverage rules updated annually each January.
Open EnrollmentMedicare Part a and Medicare Part b both participate in the annual Medicare Open Enrollment period.
Online PortalMedicare Part a and Medicare Part b both allow beneficiaries to manage coverage through the MyMedicare.gov portal.
Fraud ProtectionsMedicare Part a and Medicare Part b both include safeguards against billing fraud and identity theft.
Coverage GapMedicare Part a and Medicare Part b both leave certain services uncovered, prompting supplemental coverage needs.
Lifetime GuaranteeMedicare Part a and Medicare Part b both provide guaranteed renewable coverage for life once enrolled.

Medicare Part a or B: Which Should You Choose?

The single variable that decides it for most people is whether you still pay for employer health coverage. If you have creditable group insurance, you can delay Part B; if you do not, you need both parts to avoid lifelong late-enrollment penalties.

When to Use Medicare Part a

Choose Medicare Part a when you are still working and covered by employer insurance, because Part a is premium-free for most and covers hospital stays. Pair it with a high-deductible plan if you rarely visit hospitals, or when you want catastrophic inpatient protection without monthly premiums.

When to Use B

Choose B when you lack active employer coverage, because Part B covers doctor visits, labs, and outpatient care. Sign up during your Initial Enrollment Period if you take daily medications, see specialists regularly, or have chronic conditions, since delaying triggers a 10% premium surcharge per year.

Common Misconceptions About Medicare Part a and B

Common MythThe Reality
Medicare Part A and Part B are both completely free for everyone.Medicare Part A is free for most, but Medicare Part B always requires a monthly premium that varies by income.
You must sign up for Medicare Part A and Part B at the same time.You can enroll in Medicare Part A and Part B separately, and delaying Part B is often strategic.
Medicare Part A and Part B cover all your hospital and doctor bills fully.Medicare Part A and Part B leave significant gaps, including deductibles, coinsurance, and copayments you must pay.
Medicare Part A and Part B include coverage for routine dental, vision, and hearing care.Medicare Part A and Part B exclude most routine dental, vision, and hearing services, requiring separate supplemental plans.
Medicare Part A covers your stay in a nursing home or assisted living facility.Medicare Part A only covers short-term skilled nursing facility care, not long-term custodial care in nursing homes.
Medicare Part B covers all prescription drugs you take at home.Medicare Part B covers few outpatient drugs; most home prescriptions require a separate Medicare Part D plan.
Medicare Part A and Part B are the same as a private health insurance plan.Medicare Part A and Part B are federal programs with different rules, costs, and provider networks than private insurance.
If you are still working, you never need to enroll in Medicare Part B.You can delay Medicare Part B without penalty only if you have credible group coverage from an employer with 20+ workers.
Medicare Part A and Part B automatically start the day you turn 65.Medicare Part A and Part B start automatically only if you already receive Social Security benefits before turning 65.
Medicare Part A pays 100% of all hospital costs with no limits.Medicare Part A has a benefit period structure, a deductible, and coinsurance for hospital stays beyond 60 days.
Medicare Part B is optional, so you can skip it and never face a penalty.Delaying Medicare Part B without creditable coverage triggers a permanent 10% premium surcharge for each 12-month period.
Medicare Part A and Part B cover emergency medical care anywhere in the world.Medicare Part A and Part B generally do not cover healthcare outside the United States, except rare border or ship cases.
Medicare Part B covers annual physical exams completely for free.Medicare Part B covers one "Welcome to Medicare" visit and an annual wellness visit, but not a full physical exam.
Medicare Part A covers ambulance transportation in every emergency situation.Medicare Part A covers ambulance transport only when other transportation would endanger your health and the destination is appropriate.
Medicare Part B covers all lab tests, X-rays, and imaging without any out-of-pocket costs.Medicare Part B covers these services at 80% after the deductible, leaving you responsible for the remaining 20% coinsurance.
Medicare Part A and Part B premiums are the same for every beneficiary nationwide.Medicare Part A and Part B premiums are standard, but Part B premiums increase for high-income earners via IRMAA surcharges.
Medicare Part A covers hospice care fully, including room and board in a facility.Medicare Part A covers hospice care at home, but it does not cover room and board in a hospice facility or nursing home.
Medicare Part B covers chiropractic care, acupuncture, and massage therapy routinely.Medicare Part B covers only medically necessary chiropractic for spinal subluxation and limited acupuncture for chronic low back pain.
Medicare Part A and Part B are free for spouses of retired workers.Medicare Part A is premium-free for spouses based on a worker's record, but Medicare Part B still requires monthly premiums.
Medicare Part B covers durable medical equipment like wheelchairs at no cost to you.Medicare Part B covers durable medical equipment at 80% after the deductible, and you must rent or buy from approved suppliers.
Medicare Part A covers all inpatient rehabilitation and long-term hospital care fully.Medicare Part A covers inpatient rehab only under strict conditions, with coinsurance starting after day 60 in a benefit period.
Medicare Part B covers telehealth visits exactly the same as in-person doctor visits.Medicare Part B covers telehealth broadly now, but some services still require an in-person visit and specific originating sites.
Medicare Part A and Part B are administered by private insurance companies you choose.Medicare Part A and Part B are administered by the federal government, though private companies process claims as contractors.
Medicare Part B covers all cancer screenings, including full-body scans, at no cost.Medicare Part B covers specific preventive screenings like mammograms and colonoscopies, but not full-body CT scans for screening.
Medicare Part A covers blood transfusions completely, including the cost of the blood itself.Medicare Part A covers blood transfusions in the hospital, but you pay for the first three pints of blood unless donated.
Medicare Part B covers all doctor visits, including routine check-ups with any specialist.Medicare Part B covers medically necessary specialist visits, but you pay 20% coinsurance and there is no out-of-pocket maximum.
Medicare Part A and Part B are the only coverage you need once you turn 65.Medicare Part A and Part B leave major gaps, so most beneficiaries add Medigap, Part D, or Medicare Advantage for full protection.
Medicare Part B covers emergency room visits completely, including the facility fee and doctor fee.Medicare Part B covers the doctor fee at 80%, but the hospital facility fee falls under Part A, each with separate deductibles.
Medicare Part A and Part B have no enrollment deadlines, so you can sign up any time.Medicare Part A and Part B have specific enrollment periods; missing them causes late penalties and delayed coverage start dates.
Medicare Part A covers all home health care services, including 24-hour home care and meals.Medicare Part A covers only part-time skilled home health care, not 24-hour care, custodial care, or delivered meals.

Conclusion

Difference Between Medicare Part a and B comes down to coverage: Part a covers hospital stays, while Part b covers doctor visits and outpatient care. Choose Part a for inpatient needs. Choose Part b for everyday medical services. Most people need both.

FAQs on Difference Between Medicare Part a and B

What is the main difference between Medicare Part a and B?
Part a covers inpatient hospital stays, skilled nursing facility care, and some home health care, while Part B covers doctor visits, outpatient services, and preventive care.
Is Medicare Part a or B better for coverage?
Neither is better because they cover different services, so you typically need both to protect against major hospital costs and routine medical expenses.
How much does Medicare Part a cost per month?
Most people pay nothing for Part a if they worked and paid Medicare taxes for at least 10 years, but others may pay up to $505 monthly in 2024.
What is the monthly premium for Medicare Part B?
The standard Part B premium is $174.70 per month in 2024, though higher-income beneficiaries pay more through income-related monthly adjustment amounts.
What happens if you delay enrolling in Medicare Part B?
You may face a 10% late enrollment penalty for each full 12-month period you delay, and that penalty lasts as long as you keep Part B coverage.
Can you have Medicare Part a without Part B?
Yes, you can enroll in Part a alone, but you will pay 100% of costs for doctor visits and outpatient services unless you have other creditable coverage.
Does Medicare Part a cover prescription drugs?
No, Part a only covers drugs administered during an inpatient hospital stay, so you need Part D or a Medicare Advantage plan for outpatient prescriptions.
What is a common mistake people make with Part a and B?
A common mistake is skipping Part B while still working, which can trigger late penalties and coverage gaps if your employer coverage ends unexpectedly.
Can you switch between Medicare Part a and Part B?
You cannot switch between them because they are complementary parts of Original Medicare, but you can change how you receive benefits through Advantage plans.
How do Part a and B work together for a hospital stay?
Part a pays for your inpatient hospital room and nursing care, while Part B pays for the doctor services you receive during that same hospital stay.