27 CFR 70.25 - Special procedures for third-party summonses.
(a) When the Bureau summons the records of persons defined by 26 U.S.C. 7609(a)(3) as “third-party recordkeepers”, the person about whom information is being gathered must be notified in advance, except when:
(2) The summons is served to determine whether or not records of the business transactions or affairs of an identified person have been made or kept, or
(4) The appropriate TTB officer petitions, and the court determines, on the basis of the facts and circumstances alleged, that there is reasonable cause to believe the giving of notice may lead to attempts to conceal, destroy, or alter records relevant to the examination, to prevent the communication of information from other persons through intimidation, bribery, or collusion, or to flee to avoid prosecution, testifying or production of records.
(b) Within 3 days of the day on which the summons was served, the notice required by paragraph (a) of this section shall be served upon the person entitled to notice, or mailed by certified or registered mail to the last known address of such person, or, in the absence of a last known address, left with the person summoned. No examination of any records required to be produced under a summons as to which notice is required under paragraph (a) of this section may be made:
(1) Before the close of the 23rd day after the day notice with respect to the summons is given in the manner provided in this paragraph, or
(2) Where a proceeding under paragraph (c) of this section was begun within the 20-day period referred to in that paragraph and the requirements of paragraph (c) of this section have been met, expect in accordance with an order of the court having jurisdiction of such proceeding or with the consent of the person beginning the proceeding to quash.
(c) If the person about whom information is being gathered has been given notice, that person has the right to institute, until and including the 20th day following the day such notice was served on or mailed, by certified or registered mail, to such notified person, a proceeding to quash the summons. During the time the validity of the summons is being litigated, the statutes of limitation are suspended under 26 U.S.C. 7609(e). Title 26 U.S.C. 7609 does not restrict the authority under 26 U.S.C. 7602 (or under any other provision of law) to examine records and witnesses without serving a summons and without giving notice of an examination.