48 C.F.R. § 1009.7001
As used in this subpart-
Authorized representative(s) of the offeror means the person(s) identified to the Internal Revenue Service (IRS) within the consent to disclosure by the offeror as authorized to represent the offeror in disclosure matters pertaining to the offer.
Delinquent Federal tax liability means any unpaid Federal tax liability that has been assessed, for which all judicial and administrative remedies have been exhausted or have lapsed, and that is not being paid in a timely manner pursuant to an agreement with the authority responsible for collecting the tax liability.
Tax check means an IRS process that accesses and uses taxpayer return information to support the Government's determination of an offeror's eligibility to receive an award, including but not limited to implementation of the statutory prohibition of making an award to corporations that have a delinquent Federal tax liability (see FAR 9.104-5(b)).
48 C.F.R. § 1009.7001