Medicare Part A is the part of Medicare that pays for hospitalization. Sometimes called “hospital insurance,” Part A covers inpatient stays at hospitals, including your room, meals, nursing care, and medications you receive during your stay. Most people don’t pay a monthly premium for Part A if they or a spouse paid Medicare taxes for at least 10 years, but you will owe a deductible and possible coinsurance when you’re actually admitted.
What Part A Covers During a Hospital Stay
Once you’re formally admitted as an inpatient, Part A kicks in to cover semi-private rooms, meals, general nursing care, drugs administered as part of your treatment, and other hospital services and supplies related to your stay. This includes things like operating room costs, lab work done during your admission, and medical devices used in your care.
Part A does not cover everything you might encounter in a hospital. Private rooms aren’t covered unless medically necessary. Personal comfort items like television and phone service in your room come out of your own pocket. And your doctors’ professional fees, even while you’re an inpatient, are actually billed separately under Part B.
What You’ll Pay Out of Pocket in 2025
Part A uses a “benefit period” structure rather than a simple annual deductible. Each benefit period begins the day you’re admitted and ends after you’ve been out of the hospital (and out of any skilled nursing facility) for 60 consecutive days. Every time a new benefit period starts, the deductible resets.
In 2025, the Part A inpatient hospital deductible is $1,676. That single payment covers the first 60 days of your hospital stay within one benefit period. If your stay stretches beyond that, coinsurance applies: $419 per day for days 61 through 90. After day 90, you begin drawing on 60 “lifetime reserve days,” which cost $838 per day. Once those lifetime reserve days are used, they don’t come back, and Part A stops covering additional days.
For most hospital stays, which last well under 60 days, the deductible is the only cost on the Part A side. A five-day stay and a forty-day stay within the same benefit period both cost the same $1,676 deductible under Part A (though you’d still owe Part B costs for physician services).
Inpatient vs. Observation: A Critical Distinction
Not everyone who spends a night in the hospital is considered an inpatient. If your doctor hasn’t written a formal admission order, you may be classified as under “observation,” which is technically an outpatient status. This distinction matters because observation services are covered under Part B, not Part A, which changes your cost-sharing and can affect your eligibility for follow-up care.
The general rule is that inpatient admission is appropriate when you’re expected to need two or more midnights of medically necessary hospital care. But even if you spend two or three nights in the hospital, you’re only an inpatient if a doctor has ordered your admission and the hospital has formally admitted you. You can stay overnight and still be classified as outpatient.
If you’re placed under observation for more than 24 hours, the hospital is required to give you a written notice called a Medicare Outpatient Observation Notice (MOON). Pay attention to this document. It tells you that you’re being treated as an outpatient, which means Part B rules apply and your time in the hospital won’t count toward the three-day inpatient requirement needed for skilled nursing coverage afterward.
Why Your Hospital Status Affects Nursing Home Coverage
Part A also covers stays in skilled nursing facilities, but only after a qualifying hospital stay of at least three consecutive inpatient days. The count starts the day you’re admitted as an inpatient and does not include the day you’re discharged. Days spent under observation status don’t count toward this requirement.
This is where the inpatient-versus-observation distinction has its biggest practical impact. Someone who spends four nights in the hospital under observation and then needs rehab at a skilled nursing facility could find that Part A won’t cover the nursing facility at all, because they were never technically an inpatient. You’d be responsible for the full cost out of pocket.
If you do have a qualifying three-day inpatient stay, you generally need to enter the skilled nursing facility within 30 days of leaving the hospital, and the care must be related to your hospital stay. Some Medicare Advantage plans and certain Medicare programs can waive the three-day requirement, so it’s worth asking your doctor or hospital staff whether a waiver applies in your situation.
Psychiatric Hospital Stays Have a Lifetime Cap
Part A covers inpatient mental health care at general hospitals with the same benefit period rules as any other hospitalization. However, if you’re treated at a freestanding psychiatric hospital rather than a general hospital’s psychiatric unit, Part A imposes a lifetime limit of 190 days. Once you’ve used those 190 days across your entire lifetime, Part A will no longer pay for care at a psychiatric hospital, though coverage at a general hospital’s psychiatric ward would still be available.
How Medicare Advantage Handles Hospital Costs
If you’re enrolled in a Medicare Advantage plan (Part C) rather than Original Medicare, your hospital coverage works differently in practice, even though the plan is required to cover at least what Part A covers. Instead of the standard Part A deductible and coinsurance structure, Advantage plans often charge a per-day copay for hospital stays. The specific amounts vary by plan.
One notable difference: Medicare Advantage plans are required to cap your total yearly out-of-pocket spending, something Original Medicare does not do. Once you hit that cap, which may differ for in-network and out-of-network services, the plan covers 100% of your costs for the rest of the year. If you’re facing a long or expensive hospitalization, this annual maximum can provide significant financial protection that Original Medicare alone doesn’t offer.
Part A vs. Part B in the Hospital
Even during an inpatient stay covered by Part A, Part B plays a role. Part A covers the facility costs: your room, nursing, hospital-administered medications, and supplies. Part B covers the professional services you receive, including your doctor’s visits, surgeon’s fees, and any specialist consultations. You’ll typically see separate charges from the hospital (Part A) and from individual physicians (Part B).
Part A also reaches back to cover most outpatient services you received at the same hospital in the three days before your admission. So if you had lab work or imaging done as an outpatient right before being admitted, those charges generally get rolled into your Part A inpatient claim rather than being billed separately under Part B.