48 CFR § 35.003 - Policy.
(a) Use of contracts. Contracts shall be used only when the principal purpose is the acquisition of supplies or services for the direct benefit or use of the Federal Government. Grants or cooperative agreements should be used when the principal purpose of the transaction is to stimulate or support research and development for another public purpose.
(c) Recoupment. Recoupment not otherwise required by law shall be in accordance with agency procedures.