Medicare Part A provides coverage for inpatient hospital stays, but this coverage is not limitless. The duration of coverage depends on a structured set of rules defining how benefits are measured and applied. Understanding this framework is necessary to determine the potential length and associated costs of an extended hospitalization. Coverage is structured around specific timeframes and cost-sharing requirements that change based on the length of the stay.
Understanding the Medicare Benefit Period
The fundamental concept Medicare uses to measure hospital coverage duration is the “Benefit Period.” This period is based on the patient’s pattern of care, not the calendar year. A Benefit Period begins the day you are formally admitted as an inpatient to a hospital or a Skilled Nursing Facility (SNF).
The Benefit Period remains active until you have been out of a hospital or SNF for 60 consecutive days. If readmitted before the 60-day break is complete, the stay is part of the current Benefit Period, and you do not pay the Part A deductible again. If readmitted after a break of 60 consecutive days, a new Benefit Period starts, requiring a new Part A deductible payment.
There is no limit to the number of Benefit Periods you can have over your lifetime, meaning the cycle of coverage can reset multiple times. This structure determines how many covered days you have available for each hospitalization.
Coverage Limits for Standard Inpatient Stays
Within each Benefit Period, Medicare Part A covers up to 90 days of medically necessary inpatient hospital care. These 90 days are divided into two cost-sharing tiers that affect out-of-pocket expenses. The first 60 days of an inpatient stay are covered after paying the initial Medicare Part A deductible for that Benefit Period.
For 2025, this deductible is \$1,676; once paid, Medicare covers the remaining costs for the first 60 days. The coverage structure shifts for the remaining 30 days of the standard benefit. Days 61 through 90 require a daily coinsurance payment.
In 2025, the coinsurance for days 61 through 90 is \$419 per day. This daily charge is the patient’s portion of the cost, with Medicare covering the rest of the approved hospital charges. If a patient remains hospitalized beyond the 90th day in a single Benefit Period, they must access a separate bank of coverage days.
Utilizing Lifetime Reserve Days
If an inpatient stay exceeds 90 days within a Benefit Period, Medicare offers a non-renewable pool of 60 additional days known as Lifetime Reserve Days. These days are available only once over the patient’s entire lifetime. They can be used all at once for a single long hospitalization or split across multiple Benefit Periods that surpass the initial 90-day limit.
The use of Lifetime Reserve Days involves a significantly higher daily coinsurance payment. For 2025, the coinsurance for each Lifetime Reserve Day used is \$838. Because these days are a finite resource, hospitals must notify patients before they are used, allowing the patient to choose whether to tap into this reserve or save the days for a future illness.
Once all 60 Lifetime Reserve Days are exhausted, Medicare Part A coverage for that inpatient stay ends completely. If the patient must remain in the hospital beyond the 150th day (90 standard days plus 60 reserve days), they become responsible for 100% of all hospital costs for the duration of the stay.
Inpatient Admission Versus Observation Status
A critical distinction impacting the length of covered hospital stay is the difference between formal “Inpatient Admission” and “Observation Status.” A patient is considered an inpatient only when a doctor formally writes an order to admit them, typically expecting the stay to cross at least two midnights. Inpatient status triggers coverage under Medicare Part A, subject to the Benefit Period limits.
Observation Status is considered an outpatient service, even if the patient is in a hospital bed for multiple nights. This care is covered under Medicare Part B (medical insurance), meaning the Part A Benefit Period limits do not apply. While Observation Status has no specific time limit, it can lead to different and higher out-of-pocket costs. Part B typically requires a 20% coinsurance for each service, and medications a patient usually takes at home may not be covered.
The classification is also vital because it affects qualification for subsequent care in a Skilled Nursing Facility (SNF). To qualify for Medicare Part A coverage of a SNF stay, the patient must have had an inpatient hospital stay of at least three consecutive days. Time spent under Observation Status does not count toward this mandatory three-day requirement, potentially resulting in the patient paying the full cost of needed post-hospital SNF care.