2018 Medicare Trustees Annual Report

"The Medicare program has two separate trust funds, the Hospital Insurance Trust Fund (HI) and the Supplementary Medical Insurance Trust Fund (SMI). HI, otherwise known as Medicare Part A, helps pay for hospital, home health services following hospital stays, skilled nursing facility, and hospice care for the aged and disabled. SMI consists of Medicare Part B and Part D. Part B helps pay for physician, outpatient hospital, home health, and other services for the aged and disabled who have voluntarily enrolled. Part D provides subsidized access to drug insurance coverage on a voluntary basis for all beneficiaries and premium and cost-sharing subsidies for low-income enrollees. Medicare also has a Part C, which serves as an alternative to traditional Part A and Part B coverage. Under this option, beneficiaries can choose to enroll in and receive care from private Medicare Advantage and certain other health insurance plans. Medicare Advantage and Program of All-Inclusive Care for the Elderly (PACE) plans receive prospective, capitated payments for such beneficiaries from the HI and SMI Part B trust fund accounts; the other plans are paid from the accounts on the basis of their costs.."
Medicare report