Mo. Rev. Stat. § 136.170: Delinquent accounts — penalty.

If any of the persons mentioned in section 136.160 shall fail to pay the amounts so found due to the director of revenue after settlement and adjustment thereof, and after agreement thereto as for an account stated, within thirty days after the settlement above required, the delinquent shall forfeit to the state the amount of the commission thereon allowed him by law, and also two and a half percent a month on the amount wrongfully withheld, to be computed from the time the same ought to have been paid until actual payment; and the director of revenue shall charge such delinquent accordingly.