(a) Every motor carrier shall keep such records as may be necessary for the effective administration of this article and for the reporting and justification of the amount of tax liability pursuant to this article. All such records shall be kept in the form required by the commissioner and shall be safely preserved for a period of three years in such a manner as to ensure their security and availability for inspection by the commissioner or his authorized agents. Upon application in writing after an audit of the motor carrier's records has been made, the commissioner may consent to the destruction of the records within the three-year period.

(b) The commissioner and his authorized agents and representatives may inspect during regular business hours the books and records of any motor carrier subject to the road tax imposed by this article.

(c) Whenever any motor carrier neglects or refuses to file any report or neglects or refuses to keep records as prescribed by this article, the commissioner, using the best information available, shall estimate, determine, and fix the amount of taxes and penalties payable by the motor carrier under this article. In any action or proceeding under this Code section, any assessment by the commissioner shall constitute prima-facie evidence of the claim of the state. The burden of proof shall be upon the motor carrier to show that the assessment was incorrect or contrary to law.

(d) The commissioner may enter into agreements with the appropriate authorities of other jurisdictions having statutes similar to this article for the cooperative audit of motor carriers' reports and returns. In performing any such audit or part of an audit, the officers and employees of the other jurisdiction or jurisdictions shall be deemed authorized agents of this state for such purpose.