The chief procurement officer shall propose regulations for approval by the procurement commission setting forth cost principles which shall be used to determine the allowability of incurred costs for the purpose of reimbursing costs under contract provisions that provide for the reimbursement of costs; provided, that if a written determination is made by the chief procurement officer to justify such action, such cost principles may be modified by contract and reported to the comptroller of the treasury.
T.C.A. § 12-3-603