48 CFR §14.408-3

1. (a)Prompt payment discounts shall not be considered in the evaluation of bids. However, any discount offered will form a part of the award, and will be taken by the payment center if payment is made within the discount period specified by the bidder. As an alternative to indicating a discount in conjunction with the offer, bidders may prefer to offer discounts on individual invoices.
2. (b)See 32.111(b)(1), which prescribes the contract clause at 52.232-8, Discounts for Prompt Payment.