25 U.S. Code § 4011 - Responsibility of Secretary to account for daily and annual balances of Indian trust funds
The Secretary shall account for the daily and annual balance of all funds held in trust by the United States for the benefit of an Indian tribe or an individual Indian which are deposited or invested pursuant to section 162a of this title.
The Secretary shall cause to be conducted an annual audit on a fiscal year basis of all funds held in trust by the United States for the benefit of an Indian tribe or an individual Indian which are deposited or invested pursuant to section 162a of this title, and shall include a letter relating to the audit in the first statement of performance provided under subsection (b) after the completion of the audit.
Provisions stating that the Secretary was not required to provide a quarterly statement of performance for any Indian trust account that had not had activity for at least 18 months and had a balance of $1.00 or less but was required to issue an annual account statement and maintain a record of any such accounts and to permit the balance in each such account to be withdrawn upon the express written request of the account holder, were contained in Department of the Interior, Environment, and Related Agencies Appropriations Act, 2006, Pub. L. 109–54, title I, Aug. 2, 2005, 119 Stat. 519, and were repeated in provisions of subsequent appropriations acts which are not set out in the Code. Similar provisions were also contained in the following prior appropriations acts: