How Missouri Courts Determine Child Support and When Modifications Are Allowed

Navigating child support can be a complex and emotional aspect of a divorce or custody case. At Columbia Family Law Group,LLC, our experienced attorneys understand the importance of ensuring that child support arrangements are fair and comply with Missouri law. With over 35 years of experience, we help our clients understand how courts calculate child support and when changes may be justified.
How Missouri Calculates Child Support
Missouri uses an income-sharing model to determine child support payments. This method is designed to reflect the financial contribution that both parents would make if they lived together. The calculation takes into account each parent’s gross income, child care costs, health insurance for the child, and other relevant factors.
The primary tool used by courts in Missouri is Form 14, which is a standardized worksheet outlined in Supreme Court Rule 90.09. This form helps judges and attorneys calculate the presumed amount of child support based on several factors, including:
- Each parent’s monthly gross income, including wages, bonuses, commissions, and certain government benefits;
- The number of children involved in the case;
- The cost of health insurance and childcare related to work;
- Any existing child or spousal support obligations from previous relationships;
- The number of nights the child spends with each parent in shared custody arrangements.
While Form 14 provides guidelines, Missouri courts have the discretion to deviate from the calculated amount if they believe it is in the best interests of the child, in accordance with Section 452.340 of the RSMo (Missouri Revised Statutes).
When Can Child Support Be Modified?
Child support orders are not fixed. Missouri law acknowledges that life situations can change, such as losing a job, fluctuating income, or evolving children’s needs. Under Section 452.370 of the RSMo, either parent can request a change to child support if there has been a “significant and ongoing change in circumstances” that makes the current arrangement unreasonable.
Common reasons for modification include:
- Significant changes in either parent’s income (usually a 20% change or more)
- Changes in a child’s needs due to medical conditions that require ongoing care
- Changes to custody or parenting arrangements
- Loss of employment or disability that affects earning capacity
It’s important to note that any modification of child support payments is not automatic. Any changes must be requested formally through the court system. Informal agreements between parents, even if they are well-intentioned, are not legally binding unless approved by a court. Attempting to reduce or stop child support payments without court approval could lead to contempt charges, garnishment of wages, or even suspension of your driver’s license.
The Modification Process in Missouri

To request a modification, a parent must file a motion to modify child support with the court that issued the original order. The party filing the motion has the responsibility of proving that there has been a significant change since the previous order was issued.
Missouri courts will generally not consider modifications to child support unless:
- It has been at least 12 months since the last court order (unless the current order does not include a calculation based on Form 14); and
- The change in circumstances leads to a proposed support amount that is at least 20% different from the current amount (Section 452.370.4 of the Missouri Revised Statutes).
Once a case has been filed, the court may order temporary changes to support while the case is being heard. This typically requires updated financial information, such as pay stubs and tax returns, from both parties involved.
Why Legal Representation Matters
Child support determinations and modifications require a detailed financial analysis and adherence to strict procedural rules. Mistakes, such as failing to update income information or miscalculating Form 14, can lead to unfavorable results. An experienced divorce attorney in Columbia can help protect your rights and ensure that your child’s best interests are at the heart of the process.
At Columbia Family Law Group LLC, we provide guidance to our clients throughout every stage of the child support process, from initial calculations to post-decree modifications. Thanks to our deep understanding of the Missouri family court system and our commitment to personalized service, you don’t have to face these challenges alone.
If your financial circumstances have changed or you think the current child support arrangement no longer makes sense, contact us. We’re here to help you find a fair and legal solution that will support your child’s future and help you feel more at peace.


