The Social Security trust funds are financial accounts in the U.S. Treasury.
There are two separate Social Security trust funds, the Old-Age and Survivors
Insurance (OASI) Trust Fund pays retirement and survivors benefits, and the
Disability Insurance (DI) Trust Fund pays disability benefits.

Social Security taxes and other income are deposited in these accounts, and
Social Security benefits are paid from them. The only purposes for which these
trust funds can be used are to pay benefits and program administrative costs.

The Social Security trust funds hold money not needed in the current year to
pay benefits and administrative costs and, by law, invest it in special Treasury
bonds that are guaranteed by the U.S. Government. A market rate of interest is
paid to the trust funds on the bonds they hold, and when those bonds reach
maturity or are needed to pay benefits, the Treasury redeems them.