48 CFR § 31.202 - Direct costs.
(a) No final cost objective shall have allocated to it as a direct cost any cost, if other costs incurred for the same purpose in like circumstances have been included in any indirect cost pool to be allocated to that or any other final cost objective. Direct costs of the contract shall be charged directly to the contract. All costs specifically identified with other final cost objectives of the contractor are direct costs of those cost objectives and are not to be charged to the contract directly or indirectly.
(b) For reasons of practicality, the contractor may treat any direct cost of a minor dollar amount as an indirect cost if the accounting treatment -
(1) Is consistently applied to all final cost objectives; and
(2) Produces substantially the same results as treating the cost as a direct cost.