48 CFR §326.607-1

1. (a)The CO can accept an offeror's written representation of being an ISBEE or IEE (as defined in HHSAR 326.601) only when it is submitted in response to a Sources Sought Notice, Request for Information (RFI) or with an offer in response to a solicitation under the Buy Indian Act. Another interested party may challenge the representation of an offeror or awardee by filing a written challenge.
2. (b)Upon receipt of the challenge, the CO shall re-verify the representation of the offeror or awardee in accordance with the requirements of this subpart, including the provisions of 326.606.