What is the U.S. Social Security Trust Fund?

In the United States, there are only three types of social insurance programs, namely, the Old-Age Social Security (OASDI) program, the Social Security (Medicare) program, and the federal/state unemployment insurance programs. Accordingly, the contribution income and benefit expenses of each type of program are recorded and managed by three major funds under the control of the Department of the Treasury. These three funds are: (1) Social Security Fund. Americans call "Social Security Trust Fund", directly translated as "Old Age, Survivors and Disability Insurance Trust Fund" (also known as OASDI Trust Fund). It is composed of two sub-funds, the OASI Trust Fund and the DI Trust Fund. The OASI Trust Fund, or Old-Age, Survivors Insurance Trust Fund, was created by Section 201 of the Social Security Act Amendments of 1939. This amendment also created the Board of Trustees of the Trust Fund.The OASI was implemented (effective) on January 1, 1940, and replaced the Old Age Reserve Account established under the Social Security Act of 1935.The OASI Trust Fund provides automatic financial spending authority to pay monthly benefits to retired worker beneficiaries and their spouses and children, as well as to survivors of deceased disabled workers. The DI Trust Fund, or Disability Insurance Trust Fund, was created by the Social Security Act Amendments of 1956.DI became (effective) on January 1, 1957.The DI Trust Fund also provides automatic financial spending authority and pays monthly benefits to disabled worker beneficiaries and their spouses and children. (2) Social Security Medicare Fund. Known to Americans as the Medicare Trust Fund. It is also made up of two subfunds: the Hospitalization (HI) Trust Fund and the Supplemental Medical Insurance (SMI) Trust Fund. The Medicare program was established by the Social Security Amendments Act of 1965, "Health Insurance for the Aged". The Medicare program consists of two parts: Part A, Hospital Insurance (HI), which pays for hospital and related services for inpatients; and Part B, Supplemental Medical Insurance (SMI), which pays for physician and outpatient services. Beginning January 1, 2006, SMI added a new member, Part D, the Prescription Drug Plan (PDP), which primarily provides new prescription drug benefits. Thus, the HI Trust Fund corresponds to the Part A program; the SMI Trust Fund corresponds to the two sub-plans, Part B and Part D. (3) Federal/State Unemployment Insurance Fund. Also known as the UI Trust Fund, it is comprised of three main accounts: the Federal Employment Insurance Administration Account (ESAA), the Federal Supplemental Unemployment Insurance Account (EUCA), and the Federal Unemployment Account (FUA). Unlike the above two types of trust funds, the U.S. unemployment insurance system is a social insurance program administered by the federal government in conjunction with state governments***. Among them, the unified federal unemployment insurance law is enforced by the Employment and Training Administration (ETA) and the Unemployment Insurance Service (UIS) under the Department of Labor (DOL); and states are specifically responsible for the implementation of the unemployment insurance law.