31 USC 3106 – Retirement and savings bonds
(a) With the approval of the President, the Secretary of the Treasury may issue retirement and savings bonds of the United States Government and may buy, redeem, and make refunds under section 3111 of this title. The proceeds from the bonds shall be used for expenditures authorized by law. Retirement and savings bonds may be issued only on a discount basis. The maturity period of the bonds shall be at least 10 years from the date of issue but not more than 30 years from the date of issue. The difference between the price paid and the amount received on redeeming a bond is interest under the Internal Revenue Code of 1986 (26 U.S.C. 1 et seq.).
(b) With the approval of the President, the Secretary may allow owners of retirement and savings bonds to keep the bonds after maturity and continue to earn interest on them at rates that are consistent with the rate of investment yield provided by retirement and savings bonds.
(c) Section 3105(c)(1)-(5) of this title applies to this section. Sections 3105(c)(6) and (d) and 3126 of this title apply to this section to the extent consistent with this section. The Secretary may prescribe the maximum amount of retirement and savings bonds issued under this section in a year that may be held by one person. However, the maximum amount shall be at least $3,000.