Child Support
Mo. Rev. Stat. § 452.340 — the guidelines amount is presumed correct, and support can run to twenty-one in school
In any court or administrative proceeding for child support, the amount the guidelines produce is presumed to be the correct amount, and it is also presumed to be the amount owed for the period before the petition was filed.
Who handles this in Missouri: legal aid programs and the state offices, listed in the Missouri directory.
- A child still enrolled in and attending a secondary school program at eighteen is supported while progressing toward completion, until the program is finished or the child reaches age twenty-one, whichever comes first.
- A child who enrolls in vocational or higher education by October first after graduating, completes at least twelve hours of credit each semester and keeps grades good enough to reenroll is supported until finishing or reaching age twenty-one, and gives each parent a transcript at the start of each semester.
- Unless the order says otherwise for a reason the section allows, the obligation ends at age twenty-one without further process.
Changing an order. Where applying the guidelines and supreme court rules to the parents' current finances would change support by twenty percent or more from an amount that was based on the guidelines, that is a prima facie showing of a change so substantial and continuing that the existing terms are unreasonable.
The guidelines and their worksheet are set by supreme court rule rather than in the statute. How they apply to a particular household are questions for a licensed Missouri attorney.
Sources for this section (2)
- Mo. Rev. Stat. § 452.340 — Child support, how allocated
- Mo. Rev. Stat. § 452.370 — Modification of judgment as to maintenance or support
Legal information, not legal advice. Verified as of October 2026. Applying it to a particular situation is the work of a licensed Missouri attorney.