13 CFR §121.405

1. (a)A concern must self-certify it is small under the size standard specified in the solicitation, or as clarified, completed or supplied by SBA pursuant to § 121.402(d).
2. (b)A contracting officer may accept a concern's self-certification as true for the particular procurement involved in the absence of a written protest by other offerors or other credible information which causes the contracting officer or SBA to question the size of the concern.
3. (c)Procedures for protesting the self-certification of an offeror are set forth in §§ 121.1001 through 121.1009.