18 C.F.R. § 341.13
(b) Tariff publications that are subject to investigation. A tariff publication that has been permitted to become effective subject to investigation may be withdrawn at any time by filing a notice with the Commission, which includes a transmittal letter, a certification that all subscribers have been notified of the withdrawal, and the previous tariff provisions that are to be reinstated upon withdrawal of the tariff publication under investigation. Such withdrawal shall be effective immediately upon the submission of the notice, unless a specific effective date is set forth in the notice, and must have the following effects:
[Order 561, 58 FR 58773, Nov. 4, 1993, as amended by Order 714, 73 FR 57537, Oct. 3, 2008; Order 780, 78 FR 32099, May 29, 2013]