Okla. Stat. tit. 63, § 684.10

ARTICLE IX Reimbursement Any party state rendering aid in another state pursuant to this compact shall be reimbursed by the party state receiving such aid for any loss or damage to or expense incurred in the operation of any equipment and the provision of any service in answering a request for aid and for the costs incurred in connection with such requests; provided, that any aiding party state may assume in whole or in part such loss, damage, expense, or other cost, or may loan such equipment or donate such services to the receiving party state without charge or cost; and provided further, that any two or more party states may enter into supplementary agreements establishing a different allocation of costs among those states. Article VIII expenses shall not be reimbursable under this article.