Medicare Part A covers institutional care in hospitals and skilled nursing facilities, as well as certain care given by home health agencies and care provided in hospices.

Any person who has reached age 65 and who is entitled to Social Security benefits is eligible for Medicare Part A without charge. That is, there are no premiums for this part of the Medicare program.

Medicare pays for 90 days of hospital care per "spell of illness," plus an additional lifetime reserve of 60 days. A single "spell of illness" begins when the patient is admitted to a hospital or other covered facility, and ends when the patient has gone 60 days without being readmitted to a hospital or other facility. There is no limit on the number of spells of illness. However, the patient must satisfy a deductible before Medicare begins paying for treatment. This deductible, which changes annually, is $1,340 in 2018.

After the deductible is satisfied, Medicare will pay for virtually all hospital charges during the first 60 days of a recipient's hospital stay, other than telephone and television expenses. What Medicare covers includes:

• a bed in a semiprivate room, meaning a room with at least one other patient. (Medicare will pay for a private room only if it is "medically necessary.")
• all meals
• regular nursing services
• operating room, intensive care unit, or coronary care unit charges
• medical supplies
• drugs furnished by the hospital
• laboratory tests
• x-rays
• the use of appliances
• medical social services
• physical and occupational therapy
• speech therapy
• blood transfusions after the first three pints of blood

However, Medicare will not pay for treatments or procedures that it considers medically unproven or experimental.

If the hospital stay extends beyond 60 days, the Medicare beneficiary begins shouldering more of the cost of his or her care. From day 61 through day 90, the patient pays a coinsurance of $335 a day in 2018. Beyond the 90th day, the patient begins to tap into his or her 60-day lifetime reserve. During hospital stays covered by these reserve days, beneficiaries must pay a coinsurance of $670 per day in 2018. This reserve is not reset after each "spell of illness." Once it has been exhausted, the beneficiary will receive coverage for only 90 days when the next spell of illness occurs. However, studies show that the average length of a hospital stay covered by Medicare is eight days.

Medicare Part A also pays for stays in psychiatric hospitals, but payment is limited to a total of 190 days of inpatient psychiatric hospital services during a beneficiary's lifetime.