How to Modify Child Support in Missouri
Reviewed by DocDraft Legal Team · Missouri · Last updated September 21, 2026
In Missouri, a child support modification is a court order changing an existing child support order after circumstances change, and the state gives you a clear benchmark to measure your case. Under RSMo 452.370, a modification requires changed circumstances so substantial and continuing as to make the existing terms unreasonable, and if a fresh guideline calculation would move the amount by 20 percent or more, that is a prima facie showing of such a change when the existing amount was based on the guideline figure. Child support in Missouri is set by the statewide guidelines, known as Form 14, that weigh each parent's income, custody time, and child care and health costs (RSMo 452.340). You can seek a change two ways. You can file a Motion to Modify Child Support (Form CAFC102) in the circuit court that issued your order, or, if the Family Support Division manages your case, you can ask it to review the order, generally every three years or sooner for a substantial change. Timing matters for money: an order can be modified only as to installments that accrued after the date of personal service of your motion on the other parent, so support that already came due cannot be reduced. Keep paying your current order until a court changes it. Attorney review of your filing is available through DocDraft.
Find out where you stand in Missouri
Where are you with changing your child support order?
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How do I modify child support in Missouri?
File a Motion to Modify Child Support (Form CAFC102) in the circuit court that issued your order, or ask the Family Support Division to review your case. You must show changed circumstances so substantial and continuing that the current terms are unreasonable (RSMo 452.370).
How much must child support change to modify it in Missouri?
Under RSMo 452.370, if applying the Form 14 guidelines to current finances would change the support amount by 20 percent or more from the existing order, that is a prima facie showing of a substantial and continuing change, provided the existing amount was based on the guideline figure.
How far back can a child support change go in Missouri?
A modification reaches only installments that accrued after the date of personal service of your motion on the other parent (RSMo 452.370). Support that already came due cannot be reduced, so filing and serving promptly protects you. Keep paying the current order until a judge changes it.
Which court or agency handles child support modifications in Missouri?
The circuit court that issued your existing order handles modifications, usually through its family court division. If the Family Support Division manages your case, you can ask it to review and adjust the order, generally every three years or sooner when a substantial change occurs.
Missouri child support modification at a glance
In Missouri, a child support modification is a court or agency changing an existing support order after circumstances change. The threshold is defined in RSMo 452.370: you need changed circumstances so substantial and continuing that the current terms are unreasonable, and a fresh guideline calculation that moves the amount by 20 percent or more is a prima facie showing of that change when the existing amount followed the guideline. Support is set by the statewide Form 14 guidelines tied to income, custody time, and child care and health costs (RSMo 452.340). You file a Motion to Modify Child Support (Form CAFC102) in the circuit court that issued your order, or ask the Family Support Division to review your case, generally every three years. A change reaches only installments that accrued after the date of personal service of your motion, so past-due support cannot be reduced.
Lowering a Missouri order after a pay cut
Suppose your Missouri order was set three years ago and your income has dropped enough that a fresh Form 14 calculation would cut support by more than 20 percent, which RSMo 452.370 treats as a prima facie substantial and continuing change. You complete a Motion to Modify Child Support (Form CAFC102) with a Statement of Income and Expenses showing your lower income, and file it in the circuit court that issued your order. Because a modification reaches only installments that accrued after the date of personal service, you have the other parent served right away rather than waiting, and you keep paying the current amount until the court rules. At the hearing the court recalculates support under the guidelines and signs a lower order effective from the service date. Attorney review of your filing is available through DocDraft.
Relevant Laws
RSMo 452.370 (modification of support; 20 percent test; retroactivity)
Provides that a support order may be modified only on a showing of changed circumstances so substantial and continuing as to make the terms unreasonable, treats a 20 percent or more guideline change as a prima facie showing, and limits modification to installments that accrued after the date of personal service.
RSMo 452.340 (child support guidelines, Form 14)
Sets Missouri's child support obligation factors and directs the Supreme Court to establish the statewide guidelines, known as Form 14, used to calculate the presumed correct child support amount in judicial and administrative proceedings.
Missouri Courts: Motion to Modify Child Support
The Missouri Courts self-help page explains how to file a Motion to Modify Child Support (Form CAFC102), the related Statement of Income and Expenses (Form CAFC150), and how the other parent responds and is served.
Missouri Courts self-represent forms portal
The Missouri judiciary's self-representation site provides the child support modification forms and instructions free of charge, including Form CAFC102 and the Statement of Income and Expenses.
Regional Variances
Missouri child support modification rules at a glance
Qualifying threshold
Changed circumstances so substantial and continuing that the terms are unreasonable (RSMo 452.370). A fresh Form 14 calculation that moves the amount by 20 percent or more is a prima facie showing of that change when the existing amount was based on the guideline.
Where to file
The circuit court that issued your existing order, usually through its family court division. If the Family Support Division manages your case, you can ask it to review and adjust the order without a full court hearing.
Modification form
Form CAFC102, the Motion to Modify Child Support, with a Statement of Income and Expenses (Form CAFC150). Missouri provides these forms free through selfrepresent.mo.gov and the Missouri Courts website.
Retroactivity
A modification can reach only support installments that accrued after the date of personal service of your motion on the other parent (RSMo 452.370). Support that already came due cannot be reduced.
Periodic review
If the Family Support Division handles your case, you can generally request a review about every three years without showing a change, and sooner when a substantial and continuing change occurs.
Suggested Compliance Checklist
Gather proof of your changed circumstances
Before you file days after startingCollect current pay stubs, tax returns, and proof of the change, then estimate the new Form 14 amount to see whether it moves 20 percent or more (RSMo 452.370). Attorney review of your filing is available through DocDraft.
Complete the Motion to Modify Child Support (CAFC102)
As soon as your circumstances change days after startingFill out Form CAFC102 asking to change child support, describe the changed circumstances, and attach a Statement of Income and Expenses (Form CAFC150). Use the free Missouri Courts and selfrepresent.mo.gov forms and instructions.
File in the circuit court
Promptly, before serving the other parent days after startingFile your CAFC102 with the clerk of the circuit court that issued your order and pay the fee, or ask the court to waive it. The court opens your modification case and schedules the next steps.
Serve the other parent
As soon as the motion is filed days after startingHave the other parent personally served with your filed motion, because a change reaches only installments that accrued after the date of personal service (RSMo 452.370). File the return of service, and serve promptly to protect support you may be owed.
Consider a Family Support Division review
Anytime your case is with the division days after startingIf the Family Support Division manages your case, ask it to review your order. The division generally reviews orders every three years, or sooner for a substantial and continuing change in circumstances.
Attend the hearing and get the new order
On your hearing date days after startingBring your income proof and evidence of the change, let the court recalculate support under the Form 14 guidelines, and get the signed order effective from the date of personal service. Keep paying the current order until then.
| Task | Description | Document | Days after starting |
|---|---|---|---|
| Gather proof of your changed circumstances | Collect current pay stubs, tax returns, and proof of the change, then estimate the new Form 14 amount to see whether it moves 20 percent or more (RSMo 452.370). Attorney review of your filing is available through DocDraft. | - | Before you file |
| Complete the Motion to Modify Child Support (CAFC102) | Fill out Form CAFC102 asking to change child support, describe the changed circumstances, and attach a Statement of Income and Expenses (Form CAFC150). Use the free Missouri Courts and selfrepresent.mo.gov forms and instructions. | - | As soon as your circumstances change |
| File in the circuit court | File your CAFC102 with the clerk of the circuit court that issued your order and pay the fee, or ask the court to waive it. The court opens your modification case and schedules the next steps. | - | Promptly, before serving the other parent |
| Serve the other parent | Have the other parent personally served with your filed motion, because a change reaches only installments that accrued after the date of personal service (RSMo 452.370). File the return of service, and serve promptly to protect support you may be owed. | - | As soon as the motion is filed |
| Consider a Family Support Division review | If the Family Support Division manages your case, ask it to review your order. The division generally reviews orders every three years, or sooner for a substantial and continuing change in circumstances. | - | Anytime your case is with the division |
| Attend the hearing and get the new order | Bring your income proof and evidence of the change, let the court recalculate support under the Form 14 guidelines, and get the signed order effective from the date of personal service. Keep paying the current order until then. | - | On your hearing date |
Frequently Asked Questions
A real, involuntary income drop can support a modification if a fresh Form 14 calculation would change the amount by 20 percent or more (RSMo 452.370). You must still file a motion; support keeps accruing at the old rate until the court acts. Do not simply stop paying.
No. Either parent can file a Motion to Modify Child Support on their own, and the other parent is served and can respond. If both parents agree on a new amount, they can present a written agreement for the court to approve against the Form 14 guidelines.
After you file Form CAFC102, the circuit court sets a schedule, often several weeks to a few months depending on the county and whether the other parent contests it. An uncontested motion or a Family Support Division review can move faster. Serving promptly protects support you may be owed.
Yes. If the Family Support Division manages your case, you can ask it to review your order. The division generally reviews orders every three years, or sooner for a substantial and continuing change, and can take a proposed modification to the court for approval.
A modification reaches only installments that accrued after the date of personal service of your motion (RSMo 452.370). Support that already came due, called arrears, cannot be reduced or erased by a modification. Keep paying your current order to avoid building arrears while your motion is pending.
Filing a Motion to Modify Child Support in circuit court carries the court's filing fee, but you can ask the court to waive it if you cannot afford to pay. A review through the Family Support Division does not charge you a fee for the review itself.
You start with Form CAFC102, the Motion to Modify Child Support, and attach a Statement of Income and Expenses (Form CAFC150) with proof of your income. Missouri provides these forms and instructions free through selfrepresent.mo.gov and the Missouri Courts website.
You can file whenever a substantial and continuing change makes the current terms unreasonable (RSMo 452.370). If the Family Support Division handles your case, you can generally request a review about every three years even without a change, under federal rules. There is no limit when circumstances genuinely change.
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