One of the lesser known benefits available with Original Medicare is something called “lifetime reserve days.” The Index of Topics in the front of the 2024 “Medicare & You” consumer booklet does not include a line item for “Reserve Days,” but the subject is briefly mentioned in the booklet’s text discussing Part A covered services. Though not a prominently promoted benefit, reserve days are an important topic to understand. Here we will explain how this feature can help you.

Original Medicare Part A covers up to 90 days of inpatient hospital care for each benefit period. The first 60 days are paid in full after you (or your Medicare Supplement plan) have met the deductible ($1,632 in 2024). For days 61 through 90, you are responsible for a co-insurance amount of $408 per day (in 2024). This too may be covered by your Medicare Supplement policy if you have one.

After day 90 of hospitalization in the same benefit period, Medicare makes available an additional 60 days of coverage called lifetime reserve days. These come with a $816 per day co-insurance (in 2024), which, again, a Medicare Supplement plan will pay if you have one. What’s important to know is that these 60 reserve days can be used only once in your lifetime. Note, however, that if you use fewer than 60 of these reserve days for a single inpatient hospital stay — say you use just 35 days — you can still use the remainder (25 days) in a later benefit period. For Medicare purposes, a new benefit period begins after you have been out of the hospital for 60 days in a row, and it does restart your standard 90 days of hospital coverage under Part A. But a new benefit period does not restart your reserve days at 60.

Also be aware that if you are in the hospital for more than 90 days in a single benefit period, the hospital will automatically start deducting days from your lifetime reserve days. You can notify the hospital that you do not want to use your lifetime reserve days, but know that you will then be responsible for the full cost of your care for those days. In some situations, you may find it better to delay using your lifetime reserve days and pay the hospital’s daily charge instead. This could be a good choice, for example, if your hospital costs are less than or only a little higher than the co-insurance for lifetime reserve days, and you want to save your lifetime reserve days for future hospital stays that may be more expensive. If you do not want to use your lifetime reserve days, you should provide the hospital with written notice of your decision within 90 days of leaving.

A final important note: Medicare Supplement policies A through L pay for your hospital co-insurance associated with reserve days. These policies also provide up to an additional 365 lifetime reserve days with no co-insurance. In addition, Supplement Plans B through J will pay your full hospital deductible. The 365 additional reserve days provided by a Medicare Supplement plan are capped at that amount for a lifetime. Medicare specialist Toni King says, “A Medicare Supplement Plan (Medigap) can be a lifesaver. These plans typically cover the remaining costs that Medicare doesn’t pay for inpatient hospital stays, including all of the costs after the [initial 60] lifetime reserve days are used.”

By contrast, Medicare Advantage (MA) plans do not provide 365 additional reserve days, but they do have built-in caps on out-of-pocket costs, which cannot exceed a certain dollar amount for in-network care ($8,850 in 2024). So with a MA plan, it doesn’t matter how many days you’re hospitalized — you won’t have to pay more than the plan’s annual out-of-pocket limit for your hospitalization. Whether Original Medicare with a Medicare Supplement or a MA plan would better protect you financially could depend on just how long a hospitalization might last for you.