Original Medicare covers up to 90 days in a hospital per benefit period and offers an additional 60 days of coverage with a high coinsurance. These 60 reserve days can be used only once during your lifetime but do not have to be applied towards the same hospital stay. For example, if you need to stay in the hospital twice for 120 days each time (during different benefit periods), you can use 30 of your lifetime reserve days each time.

A benefit period begins when you enter a hospital or a skilled nursing facility, and ends when you have been out of the hospital or skilled nursing facility (SNF), or stop receiving Medicare-covered skilled services at the SNF, for at least 60 days in a row.

If you are in the hospital for more than 90 days in a single benefit period, the hospital will start deducting days from your lifetime reserve days. For example, if you are in the hospital for 95 days in a row, your last five days would be considered lifetime reserve days (unless you notify the hospital that you do not want to use your lifetime reserve days – see below). You would then have 55 lifetime reserve days left to use at a later time.

If you buy a Medicare supplemental insurance policy (Medigap plans A-J) it will pay all your hospital coinsurance plus provide up to 365 additional lifetime reserve days. (Plans B-J also pay your hospital deductible.)

You can choose not to use your lifetime reserve days.

  • If your hospital costs are only a little higher than the coinsurance for lifetime reserve days ($670 in 2018), you may 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 have to put your decision in writing and give it to the hospital within 90 days of leaving the hospital. You or your secondary insurance will be responsible for the hospital costs. If you decide to use your reserve days and later change your mind, the hospital must approve your decision.
  • If your average daily hospital costs are less than the coinsurance for lifetime reserve days, you will be responsible for the cost but you will not use up any of your lifetime reserve days.

Note: If you are in a Medicare Advantage Plan, your hospital deductible, copayments and benefit period will probably be different. Call your plan to find out what your out-of-pocket costs are for hospitalizations and what rules you have to follow in order to get coverage (for example, getting pre-authorization for any hospitalization).