48 CFR 9.103: 9.103 Policy.

(a) Purchases shall be made from, and contracts shall be awarded to, responsible prospective contractors only.

(b) No purchase or award shall be made unless the contracting officer makes an affirmative determination of responsibility. In the absence of information clearly indicating that the prospective contractor is responsible, the contracting officer shall make a determination of nonresponsibility. If the prospective contractor is a small business concern, the contracting officer shall comply with subpart 19.6, Certificates of Competency and Determinations of Responsibility. (If Section 8(a) of the Small Business Act (15 U.S.C. 637) applies, see subpart 19.8.)

(c) The award of a contract to a supplier based on lowest evaluated price alone can be false economy if there is subsequent default, late deliveries, or other unsatisfactory performance resulting in additional contractual or administrative costs. While it is important that Government purchases be made at the lowest price, this does not require an award to a supplier solely because that supplier submits the lowest offer. A prospective contractor must affirmatively demonstrate its responsibility, including, when necessary, the responsibility of its proposed subcontractors.