49 CFR § 366.2 - Form of designation.
(a) Designations shall be made on Form BOC-3 - Designation of Agents - Motor Carriers, Brokers and Freight Forwarders. Only one completed current form may be on file. It must include all States for which agent designations are required. One copy must be retained by the carrier, broker or freight forwarder at its principal place of business.
(b) All Motor Carriers, Brokers, and Freight Forwarders that are registered with FMCSA on September 30, 2016 must file their Form BOC-3 designation by no later than April 14, 2017. All other Motor Carriers, Brokers, and Freight Forwarders must file the FORM BOC-3 designation at the time of their application for registration. Failure to file a designation in accordance with this paragraph will result in deactivation of the carrier's USDOT Number.