La. Revenue and Taxation § 47:477
Before issuing a license for any semitrailer, trailer, or tandem semitrailer, the deputy secretary of the Department of Public Safety and Corrections shall require the owner to furnish the deputy secretary the serial number of each such vehicle. This serial number shall be stenciled permanently on the rear axle of each vehicle. If the semitrailer, trailer or tandem semitrailer does not have a serial number, then the office of state police shall assign to the owner a serial number and stencil that number permanently on the vehicle. The fee for this service shall be not less than five dollars if the semitrailer, trailer, or tandem semitrailer is brought into the office of state police or a state police headquarters or station for stenciling, and shall be not less than ten dollars if it is necessary for a representative of the office to perform the service in the field. This fee shall be retained by the office of state police to help defray the expenses of administering this Section. The number so assigned and stenciled shall be used in making application for and the licensing of each such vehicle. Any fees charged in excess of said fees shall be adopted pursuant to R.S. 49:950, et seq.
La. Revenue and Taxation § 47:477