210.845. 1. The provisions of any decree respectingsupport may be modified only upon a showing of changedcircumstances so substantial and continuing as to make the termsunreasonable. In a proceeding for modifications of any childsupport award, the court, in determining whether or not asubstantial change in circumstances has occurred, shall considerall financial resources of both parties, including the extent towhich the reasonable expenses of either party are, or should be,shared by a spouse or other person with whom he cohabits, and theearning capacity of a party who is not employed. If theapplication of the guidelines and criteria set forth in supremecourt rule 88.01 to the financial circumstances of the partieswould result in a change of child support from the existingamount by twenty percent or more, then a prima facie showing hasbeen made of a change of circumstances so substantial andcontinuing as to make the present terms unreasonable.
2. When the party seeking modification has met the burdenof proof set forth in subsection 1 of this section, the childsupport shall be determined in conformity with criteria set forthin supreme court rule 88.01.
(L. 1987 S.B. 328 ยง 18, A.L. 1993 S.B. 253)