Tax Law, § 503, subd. 1
A vehicle is deemed to be unladen if operated without any load whatsoever. A vehicle may carry any of the equipment included in unloaded weight and still be considered unladen. (See § 472.6, supra.) However, anything else carried by the motor vehicle is deemed to be a load. For example, a motor vehicle carrying empty containers such as oil drums, milk boxes, beer bottles, etc. or carrying rejected cargo, is deemed to be laden.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 481.7