Mo. Rev. Stat. § 142.854

Every supplier has a fiduciary duty to remit to the director the amount of tax paid to the supplier, in its role as a trustee, by any purchaser, importer, exporter or eligible purchaser. In computing the amount of motor fuel tax due, the supplier shall be entitled to a credit against the tax payable in the amount of tax paid by the supplier that was accrued and remitted to a state, but not received from an eligible purchaser. The director shall have the right to recover any unpaid tax directly from the eligible purchaser.