All lawful expenses and charges incurred by the commission and the Office of Regulatory Staff in the administration of this chapter and in performance of its duties thereunder shall be defrayed by assessments made by the Comptroller General against the gas utilities regulated thereunder and based upon the gross revenues collected by the gas utilities from their business done wholly within this State in the manner set out in § 58-3-100 for other corporations; provided, however, the assessments against municipalities, gas authorities, public service districts, or other political subdivisions of the State shall be applicable only to expenses and charges incurred in the administration and enforcement of the provisions of this article relating to gas safety requirements.

The Public Service Commission and the Office of Regulatory Staff shall certify to the Comptroller General annually on or before August first the amounts to be assessed in the format approved by the Comptroller General.