§ 137.505 RSMo — Failure to file return — duty of assessor

If any person, corporation, partnership or association shall fail to file a return as required by sections 137.485 to 137.550 , the assessor shall ascertain the true amount and value of the taxable tangible personal property of such person, corporation, partnership or association on the best information available to him and shall assess said property at ten percent above its value.