Mo. Rev. Stat. § 643.345

In the year in which an emissions inspection is required under section 643.315, a certificate of registration for a motor vehicle shall not be transferred, renewed or issued unless the application for the transfer, renewal or issuance is accompanied by a current emissions inspection certificate issued not more than sixty days prior to the date of application, except that the director of revenue shall renew a vehicle's certificate of registration without a current emissions inspection certificate accompanying the application if satisfactory documentary evidence is presented at the time of application that the registration being renewed was properly transferred within a six-month period prior to the expiration of the registration.