Sales of tangible personal property to agents of the United States government are exempt from sales tax if ownership and possession of such property transfers immediately to the United States government. Sales to contractors who are improving real property for the United States government are not considered to be sales in which ownership transfers immediately to the United States government and are therefore taxable. [See: 68 O.S. § 1356(1),(2),(3) ]
Okla. Admin. Code § 710:65-13-131