Except as provided in 1480.302, this part applies to all acquisitions, including simplified acquisitions, made by IA and by any other bureau or office of the Department of the Interior conducting acquisitions on behalf of IA or otherwise delegated the authority to conduct acquisitions under the Buy Indian Act.

IA must not use the authority of the Buy Indian Act and the procedures contained in this part to award intergovernmental contracts to Tribal organizations to plan, operate, or administer authorized IA programs (or parts thereof) that are within the scope and intent of the Indian Self-Determination and Education Assistance Act (ISDEAA) (Pub. L. 93-638). IA must use the Buy Indian Act solely to award procurement contracts to IEEs. Contracts subject to ISDEAA must follow 25 CFR part 900.