How to Register for a CT Number
The Cargo Tank (CT) number is assigned to facilities and/or individuals that manufacture, assemble, inspect, test, certify or perform welded repairs on cargo tanks or a cargo tank motor vehicles manufactured in accordance with a DOT specification or under the terms of an exemption.
You must submit a registration statement in accordance with 49 CFR § 107.503 to receive a CT number.
To do so, submit a Form MCS-150 to register for a USDOT number at the same time. If you already have a USDOT number, you can update that registration and add a CT number by completing the CT registration statement.