(a) A person licensed under this chapter or required to be licensed under this chapter, or other user, who fails to keep a record, issue an invoice, or file a return or report required by this chapter is presumed to have sold or used for taxable purposes all motor fuel shown by an audit by the comptroller to have been sold to the license holder or other user. Motor fuel unaccounted for is presumed to have been sold or used for taxable purposes. If an exporter claims an exemption under § 162.104(a)(4) or 162.204(a)(4) and fails to report subsequent tax-free sales in this state of the motor fuel for which the exemption was claimed as required by § 162.1155 or 162.2165, or to produce proof of payment of tax to the destination state or proof that the transaction was exempt in the destination state, the exporter is presumed to have not paid the destination state’s tax or this state’s tax on the motor fuel and the comptroller shall assess the tax imposed by this chapter on the motor fuel against the exporter. The comptroller may fix or establish the amount of taxes, penalties, and interest due this state from the records of deliveries or from any records or information available. If a tax claim, as developed from this procedure, is not paid, after the opportunity to request a redetermination, the claim and any audit made by the comptroller or any report filed by the license holder or other user is evidence in any suit or judicial proceedings filed by the attorney general and is prima facie evidence of the correctness of the claim or audit. A prima facie presumption of the correctness of the claim may be overcome at the trial by evidence adduced by the license holder or other user.
(b) In the absence of records showing the number of miles actually operated per gallon of motor fuel consumed, it is presumed that not less than one gallon of motor fuel was consumed for every four miles traveled. An interstate trucker may produce evidence of motor fuel consumption to establish another mileage factor. If an examination or audit made by the comptroller from the records of an interstate trucker shows that a greater amount of motor fuel was consumed than was reported by the interstate trucker for tax purposes, the interstate trucker is liable for the tax, penalties, and interest on the additional amount shown or the trucker is entitled to a credit or refund on overpayments of tax established by the audit.