If you need to remain hospitalized for more than 90 days in a single benefit period, Original Medicare will cover a portion of your costs for a total of 60 additional reserve days over the course of your lifetime. For each of these 60 lifetime reserve days, you pay coinsurance ($670 per day, in 2018), and Medicare pays the rest of the covered hospital costs.
Medicare inpatient coverage is based on how long you’re hospitalized. When you’re first admitted as an inpatient at the start of your benefit period, you pay your deductible ($1,340 in 2018), and then Medicare pays for your hospital care for 60 days, without you having to pay anything else for inpatient care.
If you’re still hospitalized after 60 days, you’ll start paying a portion of the bill, for the next 30 days. In 2018, you’ll pay $335 for each day in the hospital from day 61 to day 90.
If you’re still hospitalized after 90 days, you’ll either have to start paying the full bill yourself, or dipping in to your lifetime reserve days. If you use lifetime reserve days, you pay $670 per day (in 2018) and Medicare pays the rest. If you’re ultimately discharged from the hospital after 100 days, you will have used up 10 of your lifetime reserve days. That means you’ll have 50 remaining, which you could use in the future if you ever have another hospitalization that lasts more than 90 days.
Alternatively, Medicare Advantage plans have built-in caps on out-of-pocket costs, which can’t exceed $6,700 (not counting prescription drug costs) in 2018. So with a Medicare Advantage plan, it doesn’t matter how many days you’re hospitalized — you won’t have to pay more than the plan’s out-of-pocket limit for your hospitalization (note that Medicare Advantage plans have drawbacks too, such as limited provider networks. This article will help you figure out whether you’d be better off with Medicare Advantage or Original Medicare).