Trust funds and types of investments
The Old-Age and Survivors Insurance Trust Fund and the Disability Insurance Trust Fund comprise the Social Security trust funds. Both funds are managed by the Department of the Treasury through their Bureau of the Fiscal Service. Since the beginning of the Social Security program, all securities held by the trust funds have been issued by the Federal Government. There are two general types of such securities:

  • Special issues—available only to the trust funds
  • Public issues—marketable Treasury bonds available to the public.
The trust funds now hold only special issues, but they have held public issues in the past.

Special issue types and properties
There are two types of special issues: short-term certificates of indebtedness and long-term bonds.

  • The certificates of indebtedness are issued on a daily basis for the investment of receipts not required to meet current expenditures, and they mature on the next June 30 following the date of issue.
  • Special-issue bonds are normally acquired only when special issues of either type mature on June 30. The bonds generally have maturities ranging from one to fifteen years.1
The above properties of special issue securities are summarized in the following table.

Type of special issue Investment
frequency		 Maturity
Certificates of indebtedness Daily Next June 30
Bonds June 30 Generally 1 to 15 years1

Special issue redemption rules
When special issues need to be redeemed prior to maturity, the securities are redeemed in order of

  1. Earliest maturity date;
  2. Lowest interest rate for securities with the same maturity date.
1See section III.A of the latest Annual Report of the Board of Trustees of the Federal Old-Age and Survivors Insurance and Federal Disability Insurance Trust Funds for further discussion of the investment strategy of maturing certificates of indebtedness and bonds.