(a) The tax collectors of the various counties of this state and the tax commissioners of those counties in which the duties of the tax collector are performed by a tax commissioner shall be designated as tag agents of the commissioner for the purpose of accepting applications for the registration of vehicles. The commissioner is authorized to promulgate rules and regulations for the purpose of delegating to such tag agents the custodial responsibility for properly receiving, processing, issuing, and storing motor vehicle titles or registrations, or both.

(b) The state revenue commissioner is authorized to further designate each such tag agent as a sales tax agent for the purpose of collecting sales and use tax with respect to the casual sale or casual use of a motor vehicle. For purposes of this Code section, "casual sale" or "casual use" means the sale of a motor vehicle by a person who is not regularly or systematically engaged in making retail sales of motor vehicles and the first use, consumption, distribution, or storage for use or consumption of such motor vehicle purchased through a casual sale. As personal compensation for services rendered to the Department of Revenue with respect to the collection of such sales and use tax, each such designated tag agent shall be authorized to retain from such collection a fee of $200.00 per month. In any month in which an insufficient amount of such tax is collected to pay such fee, the amount of any such unpaid fee may be deferred until such month as sufficient collections are made. Such compensation shall be in addition to any other compensation to which such tax collector or tax commissioner is entitled.

(c) The duties and responsibilities of agents of the commissioner designated under this Code section shall be a part of the official duties and responsibilities of the county tax collectors and tax commissioners.