Medicare Part A covers hospital and inpatient care, while Part B covers doctor visits, outpatient services, and preventive care. Together, they form “Original Medicare,” and most people aged 65 or older qualify for both. Here’s exactly what each part pays for, what it costs, and what falls through the gaps.
What Part A Covers
Part A is hospital insurance. It kicks in when you’re admitted as an inpatient, and it covers the core essentials of that stay: a semi-private room, meals, general nursing care, and any drugs administered as part of your treatment. It also covers other hospital services and supplies tied to your inpatient care.
Part A does not cover private rooms (unless medically necessary), private-duty nursing, personal care items like razors or slipper socks, or separate charges for a television or phone in your room.
Beyond hospital stays, Part A covers three other major categories:
- Skilled nursing facility care. If you need rehabilitation or skilled nursing after a hospital stay, Part A covers up to 100 days per benefit period in a skilled nursing facility. There’s an important catch: you must first have a qualifying inpatient hospital stay of at least 3 consecutive days. Time spent in the emergency room or under observation does not count toward those 3 days, even if you’re there overnight. For the first 20 days, you pay nothing beyond the initial deductible. Days 21 through 100 carry a daily copay of $217 in 2026. After day 100, you’re responsible for all costs.
- Home health services. Part A covers medically necessary home health care, including skilled nursing and therapy, when ordered by a doctor.
- Hospice care. When a doctor certifies a terminal illness with a life expectancy of six months or less, Part A covers hospice care. This includes pain and symptom management, short-term inpatient care, and respite care to give family caregivers a break. You pay up to $5 per prescription for pain and symptom drugs, and 5% of the Medicare-approved amount for inpatient respite care. Once you elect hospice, Medicare no longer covers treatments intended to cure your terminal illness or prescription drugs aimed at curing (rather than managing) it. Room and board are not covered if you receive hospice care at home or in a nursing facility.
What Part A Costs
Most people pay no monthly premium for Part A. You qualify for premium-free Part A if you’re 65 or older and you (or your spouse) earned enough work credits through Social Security, generally 40 quarters or about 10 years of work. If you don’t meet that threshold, you can still buy into Part A by paying a monthly premium.
Even with premium-free Part A, you still pay a deductible each benefit period when you’re admitted to a hospital. A benefit period starts the day you’re admitted as an inpatient and ends when you’ve been out of a hospital or skilled nursing facility for 60 consecutive days. Each new benefit period triggers a new deductible.
What Part B Covers
Part B is medical insurance, covering two broad categories: medically necessary services and preventive services. Medically necessary services are those that meet accepted standards of medical practice to diagnose or treat a condition. Preventive services help catch illness early or prevent it altogether, like flu shots and cancer screenings.
The specific services covered under Part B include:
- Doctor visits and outpatient care. Office visits, specialist appointments, and outpatient procedures fall under Part B.
- Mental health and substance use treatment. This includes outpatient therapy, counseling, and treatment for substance use disorders.
- Ambulance services. When medically necessary transportation is required.
- Durable medical equipment. Part B covers a wide range of equipment you use at home with a doctor’s order. This includes wheelchairs and scooters, walkers, canes, crutches, hospital beds, oxygen equipment, CPAP machines for sleep apnea, blood sugar monitors and test strips, infusion pumps, and commode chairs.
- Limited outpatient prescription drugs. Part B covers a narrow set of drugs, typically those administered in a doctor’s office or clinic. Most prescription medications you pick up at a pharmacy fall under Part D instead.
- Clinical research. If you participate in a qualifying clinical trial, Part B helps cover associated costs.
After you meet your annual deductible, Part B typically pays 80% of the Medicare-approved amount for covered services. You’re responsible for the remaining 20%, with no cap on out-of-pocket spending unless you have supplemental coverage.
What Part B Costs
The standard monthly premium for Part B is $185.00 in 2025. If your income is above a certain threshold, you’ll pay more through an income-related adjustment. The annual deductible is $257 in 2025. Unlike Part A’s deductible, which resets with each benefit period, the Part B deductible resets once per calendar year.
Part B premiums are typically deducted automatically from your Social Security check. If you’re not receiving Social Security yet, you’ll get a bill from Medicare.
What Neither Part Covers
Original Medicare has significant gaps. Services not covered by Part A or Part B include:
- Long-term care. Custodial care in a nursing home, where you need help with daily activities but not skilled medical care, is not covered.
- Most dental care. Routine cleanings, fillings, tooth extractions, and dentures are excluded.
- Vision care. Eye exams for prescription glasses and the glasses themselves are not covered.
- Hearing aids. Hearing aids and the exams to fit them are excluded.
- Cosmetic surgery. Any procedure that isn’t medically necessary.
- Routine physical exams. Original Medicare doesn’t cover a standard annual physical, though it does cover a “Welcome to Medicare” preventive visit and yearly wellness visits, which are slightly different.
- Massage therapy.
- Concierge medicine. Retainer-based or boutique medical practices that charge annual fees for enhanced access.
Many people fill these gaps with a Medicare Supplement (Medigap) plan, a Medicare Advantage plan (Part C), or separate dental and vision policies. Prescription drug coverage requires enrolling in a Part D plan unless your Medicare Advantage plan already includes it.
How Part A and Part B Work Together
The simplest way to think about the split: Part A covers you when you’re admitted to a facility, and Part B covers you everywhere else. A surgery that requires an overnight hospital admission bills under Part A. A same-day outpatient procedure at that same hospital bills under Part B. The distinction matters because the cost-sharing rules are completely different for each part.
One area where this gets confusing is observation status. Hospitals sometimes keep patients overnight under “observation” rather than formally admitting them. That care bills under Part B, not Part A. It also means the stay won’t count toward the 3-day inpatient requirement for skilled nursing facility coverage. If you’re in the hospital and unsure of your status, you can ask whether you’ve been admitted as an inpatient or placed under observation.