48 C.F.R. § 42.702 – Purpose.

(a) Establishing final indirect cost rates under this subpart provides—
1. (1) Uniformity of approach with a contractor when more than one contract or agency is involved;
2. (2) Economy of administration; and
3. (3) Timely settlement under cost-reimbursement contracts.
(b) Establishing billing rates provides a method for interim reimbursement of indirect costs at estimated rates subject to adjustment during contract performance and at the time the final indirect cost rates are established.