Mo. Rev. Stat. § 303.210: Notice of cancellation of insurance to be given director.

When an insurance carrier has certified a motor vehicle liability policy under section 303.170 or a policy under section 303.180, the insurance so certified shall not be cancelled or terminated until at least ten days after a notice of cancellation or termination of the insurance so certified shall be filed in the office of the director of revenue, except that such policy subsequently procured and certified shall, on the effective date of its certification, terminate the insurance previously certified with respect to any motor vehicle designated in both certificates.