48 CFR § 1480.402 - Delegations and responsibility.
(a) The Secretary has delegated authority under the Buy Indian Act to the Assistant Secretary - Indian Affairs. IA exercises this authority in support of its mission and program activities and as a means of fostering Indian employment and economic development.
(b) The Secretary may delegate authority under the Buy Indian Act to a bureau or office within the Department of the Interior other than IA only in accordance with the Departmental Manual.
(c) As the head of the contracting activity, the CFO is responsible for ensuring that all IA acquisitions under the Buy Indian Act comply with the requirements of this part.