25 U.S. Code § 1166 - Costs
(a) Payment from judgment fund
All costs incident to making the payments authorized by this subchapter including the costs of payment roll preparation and such sums as may be required to distribute said funds, shall be paid by appropriate withdrawals from the judgment fund and interest on the judgment fund, using the interest fund first.
(b) Use of reverted funds
In the event that the sum of money reserved by the Secretary of the Interior to pay the costs of distributing said funds exceeds the amount actually necessary to accomplish this purpose, the money remaining shall revert to the tribes and may be advanced or expended for any purpose that is authorized and approved by the tribal governing body.