Mo. Rev. Stat. § 137.500

The assessor shall have available at his office a supply of appropriate forms or blanks on which the taxpayer's returns are to be made. For the convenience of taxpayers the assessor may mail or leave at the residence or place of business of the taxpayers the forms or blanks. The forms prescribed shall not require any affidavit or acknowledgment, but shall require the signature of the taxpayer and if the taxpayer is a corporation, the form shall require the signatures of any two officers of the corporation. Any person who willfully signs a false or fraudulent return shall be subject to the penalties provided for in sections 137.485 to 137.550.