Medicare covers inpatient hospital stays up to 90 days per benefit period, but what you pay and how long coverage lasts depends on which part of Medicare you have and how your hospital classifies your admission.
If you have Original Medicare (Part A and Part B), your hospital stay is covered as long as a doctor orders it as inpatient care and you stay in a hospital (not an outpatient facility). The length of coverage is measured in benefit periods, not calendar years. A benefit period starts the day you enter the hospital and ends 60 days after you leave — if you go back to the hospital after those 60 days, a new benefit period begins.
If you have a Medicare Advantage plan (Part C), the rules are different. Your plan must cover at least as many hospital days as Original Medicare does, but some plans cover more. You need to check your plan documents or call your plan to find out your specific coverage limits.
Key Takeaways
- Original Medicare covers up to 90 days per benefit period, with you paying a deductible for days 1–3, coinsurance for days 4–60, and higher coinsurance for days 61–90.
- A benefit period ends 60 days after you leave the hospital, so a new hospital stay after that gap starts a new benefit period with a fresh deductible.
- If you stay longer than 90 days in one benefit period, you can use lifetime reserve days — 60 additional days total across your lifetime, with higher out-of-pocket costs.
- Medicare Advantage plans must cover at least as many days as Original Medicare, but coverage rules and costs vary by plan.
- The hospital must admit you as an inpatient for Medicare to cover the stay; observation status does not count toward these limits.
How the 90-Day Limit Works in Original Medicare
Original Medicare Part A covers inpatient hospital care for up to 90 days in each benefit period. The benefit period is the key to understanding how this works: it is not a calendar year. It starts the moment you are admitted to the hospital as an inpatient and ends 60 days after you are discharged. If you go back to the hospital more than 60 days after leaving, you enter a new benefit period, and your 90-day count resets.
This means you could have two separate 90-day covered stays in the same calendar year if the gap between discharge and readmission is longer than 60 days. If you are readmitted within 60 days, the days you spent in the hospital before discharge count toward your 90-day limit for that benefit period.
Your out-of-pocket costs change depending on how many days you have used. For days 1 through 3, you pay a hospital deductible (the amount changes each year). For days 4 through 60, you pay a daily coinsurance amount. For days 61 through 90, you pay a higher daily coinsurance. If you reach day 91, you move into lifetime reserve days.
What Happens After 90 Days: Lifetime Reserve Days
If you stay in the hospital longer than 90 days in one benefit period, Original Medicare offers lifetime reserve days — an additional 60 days of coverage spread across your entire lifetime. You do not have to use them all at once, and you do not have to use them at all, but once they are used, they are gone.
The coinsurance for lifetime reserve days is higher than the coinsurance for days 61–90. Because these days are limited and non-renewable, many people save them for a serious, prolonged illness later in life. You can tell Medicare not to use your lifetime reserve days if you prefer to pay out of pocket instead, though this is rare.
After your lifetime reserve days run out, you are responsible for all hospital costs. This is why some people buy Medigap coverage (supplemental insurance) — certain Medigap plans cover some or all of the costs that Original Medicare does not.
Medicare Advantage Plans and Hospital Stay Limits
If you are enrolled in a Medicare Advantage plan, your coverage works differently. Medicare Advantage plans must cover at least the same number of inpatient hospital days as Original Medicare — meaning at least 90 days per benefit period. However, some plans cover more days, and the rules about what you pay can vary.
Your Medicare Advantage plan may have different deductibles, coinsurance amounts, or copays than Original Medicare. Some plans may waive the deductible or charge a flat copay per day instead of coinsurance. You need to review your plan's Summary of Benefits or call your plan directly to understand your specific coverage and costs.
Medicare Advantage plans also use the same benefit period definition as Original Medicare: 60 days after discharge ends the benefit period. If you switch plans during the year, your new plan will honor the benefit period that started under your old plan.
The Difference Between Inpatient and Observation Status
A critical distinction that affects your coverage: Medicare only counts days when you are admitted as an inpatient. If the hospital places you in observation status, those days do not count toward your 90-day limit, and Part A does not cover them the same way.
Observation status means the hospital is monitoring you but has not formally admitted you as an inpatient. This often happens in emergency departments or short-stay units. The hospital decides your status based on medical judgment, not your preference. If you are in observation for more than a few days, you may end up paying more out of pocket than if you were admitted as an inpatient.
If you believe you should have been admitted as an inpatient instead of placed in observation, you can file an appeal with Medicare. Ask the hospital for a written explanation of why you were placed in observation status, and contact your Medicare plan or Medicare directly if you disagree.
What Happens When Your Hospital Stay Crosses Benefit Periods
If you are admitted near the end of one benefit period and stay past the 60-day mark after discharge, your stay spans two benefit periods. The days before the benefit period ends count toward the first period's 90-day limit. The days after the new benefit period begins count toward the second period's 90-day limit.
This can work in your favor: if you use 80 days in the first benefit period and then are readmitted 70 days after discharge, you have a fresh 90 days in the new benefit period. However, if you are readmitted within 60 days, you are still in the same benefit period, and your remaining days are limited.
Costs You Will Pay During a Hospital Stay
| Days in Hospital | What You Pay (Original Medicare) |
|---|---|
| Days 1–3 | Hospital deductible (one time per benefit period) |
| Days 4–60 | Daily coinsurance amount |
| Days 61–90 | Higher daily coinsurance amount |
| Days 91+ (lifetime reserve) | Even higher daily coinsurance amount |
| After lifetime reserve days end | 100% of hospital costs |
The exact dollar amounts change each year. You can find the current deductible and coinsurance amounts on Medicare.gov or by calling 1-800-MEDICARE. Your hospital bill should itemize what Medicare paid and what you owe.
Frequently Asked Questions
Can I use my lifetime reserve days for a short stay, or should I save them?
You can use them whenever you want, but once they are gone, they are gone for life. Many people save them for a serious illness later. If you are unsure, ask your doctor whether your current condition is likely to require long hospital stays in the future. You can also tell Medicare not to use them and pay out of pocket instead.
What if I am in the hospital on December 31st and stay into January?
Your benefit period does not follow the calendar year. The days you spend in the hospital before discharge all count toward the same benefit period, regardless of what calendar year they fall in. The benefit period ends 60 days after you leave the hospital.
Does rehabilitation or skilled nursing care count toward my 90 days?
No. The 90-day limit applies only to inpatient hospital stays. If you are transferred to a skilled nursing facility or rehabilitation center, those days are covered separately under Medicare Part A, with their own limits and costs. However, you must have spent at least three days in the hospital as an inpatient to be covered for skilled nursing care.
What if my Medicare Advantage plan says it covers unlimited hospital days?
Some Medicare Advantage plans advertise unlimited inpatient hospital coverage. This means the plan will cover more than the 90 days Original Medicare covers, but you should still check your plan documents for any limits, prior authorization requirements, or network restrictions that might explore.
Can I appeal if Medicare denies coverage for my hospital stay?
Yes. If Medicare or your plan denies coverage or says your stay was not medically necessary, you have the right to appeal. Ask your hospital or plan for the appeal process and important date. You can also contact your State Health Insurance information Program (SHIP) for free help with appeals.