27 C.F.R. § 17.6
No claim, bond, tax return, or other required document executed by a person as an agent or representative is acceptable unless a power of attorney or other proper notification of signature authority has been filed with the TTB office where the required document must be filed. The appropriate TTB officer with whom the claim or other required document is filed may, when he or she considers it necessary, require additional evidence of the authority of the agent or representative to execute the document. Except as otherwise provided by this part, powers of attorney shall be filed on TTB Form 1534 (5000.8), Power of Attorney. Notification of signature authority of partners, officers, or employees may be given by filing a copy of corporate or partnership documents, minutes of a meeting of the board of directors, etc. For corporate officers or employees, TTB Form 5100.1, Signing Authority for Corporate Officials, may be used. For additional provisions regarding powers of attorney, see § 17.105 and 26 CFR part 601, subpart E.
27 C.F.R. § 17.6