25 U.S. Code § 116 - Indians 18 years of age to have right to receipt for annuity
All Indians, when they shall arrive at the age of eighteen years, shall have the right to receive and receipt for all annuity money that may be due or become due to them, if not otherwise incapacitated under the regulations of the Indian Office.
For transfer of functions of other officers, employees, and agencies of Department of the Interior, with certain exceptions, to Secretary of the Interior, with power to delegate, see Reorg. Plan No. 3 of 1950, §§ 1, 2, eff. May 24, 1950, 15 F.R. 3174,64 Stat. 1262, set out in the Appendix to Title 5, Government Organization and Employees.