Missouri Child Support Guidelines: How Support Is Calculated

In Missouri, child support is calculated using the income shares model on a standardized worksheet called Civil Procedure Form No. 14. Both parents' incomes are combined to estimate what the child would have received if the household were still together, and that total is divided between the parents based on each one's share of the combined income. When a Form 14 is filled out correctly, the amount it produces is presumed to be the correct child support figure — a presumption either parent can challenge, but only by showing the amount is unjust or inappropriate under Missouri Supreme Court Rule 88.01 and Section 452.340.9 of the Revised Statutes of Missouri.

How the Form 14 Calculation Works

Form 14 starts with each parent's gross income, combines it, and applies it to Missouri's official schedule of basic child support obligations to find the "basic" support amount for the number of children involved. That basic amount can then be adjusted for certain additional child-rearing costs, and split proportionally between the parents based on each parent's percentage share of the combined income.

Because the resulting number is only a presumed amount, a judge can deviate from it — but the law requires the deviation to be justified on the record, not simply a matter of one parent asking for a different number.

Adjustments That Can Change the Amount

Equal or Nearly Equal Parenting Time

If parents share equal or substantially equal physical custody of the child, Missouri law allows the court to adjust the basic child support amount downward by as much as fifty percent. This is not automatic — the court decides whether and how much of an adjustment is appropriate based on the actual custody arrangement, not just what the parenting plan says on paper.

The Overnight (Line 11) Adjustment

Form 14 also has a specific line — Line 11 — that adjusts the paying parent's obligation based on how many overnights per year the child spends with that parent. According to the directions for completing Form 14, this adjustment scales on a sliding basis, from roughly six percent up to about thirty-four percent, depending on the number of overnights. In practice, this means the more overnight parenting time a paying parent has, the more their support obligation is typically reduced through this line item — separate from, and in addition to, the equal-custody adjustment described above.

How Long Child Support Lasts in Missouri

Under Missouri law, the general rule is that a child support obligation ends when the child turns eighteen. But there are important exceptions built into the statute:

• If the child is still enrolled in and attending secondary school (high school) when they turn eighteen, support continues until the child graduates or turns twenty-one, whichever happens first.
• If the child enrolls in and attends a vocational program or institution of higher education that meets the requirements set out in the statute, support can continue up to age twenty-one.

Because these continuation rules depend on enrollment and attendance meeting specific statutory conditions, if your child is approaching eighteen and still in school or planning to attend a vocational or higher-education program, it's worth confirming with your Missouri court or a family law professional exactly what documentation is needed to keep support in place — the statute conditions continued support on meeting those requirements, and the details of what counts can vary by situation.

Changing an Existing Missouri Support Order

Missouri does not let either parent simply ask for a new number because their income changed a little, or because they'd prefer a different amount. The law requires a showing of changed circumstances so substantial and continuing that the current terms have become unreasonable. When a court considers a modification request, it looks at both parents' financial resources, and if a parent is unemployed or underemployed, the court can also consider that parent's earning capacity rather than just their actual current income.

Missouri law also provides a shortcut for showing that a change is substantial: if the existing support amount was based on the guidelines, and simply reapplying the current guidelines to updated numbers would change the support amount by twenty percent or more, that difference by itself is treated as a prima facie showing of a substantial and continuing change — meaning it's enough to get the modification request in front of the court, though the final decision still belongs to the judge.

Time-sensitive note: modifications are not retroactive to when circumstances changed. A Missouri support order can only be modified as to payments that come due after the other parent has been personally served with the modification motion. This means already-accrued support cannot be reduced after the fact — if you believe you're entitled to a lower payment, the clock on getting relief does not start until the other parent is formally served, so acting quickly matters.

Temporary Support While a Case Is Pending

If a divorce or legal separation case is still working its way through court, a parent does not have to wait for the final judgment to get support started. Missouri law authorizes a party to move for a temporary child support order while the case is pending, so a child isn't left without support during what can be a lengthy court process.

What Happens If Support Isn't Paid

Child support enforcement in Missouri runs on tools required by federal law as a condition of state funding. Under the federal Title IV-D program, Missouri's child-support enforcement agency has access to standardized tools including automatic income withholding from paychecks, license suspension, and liens against property to collect unpaid support. Federal law also waives sovereign immunity so that even federal wages and benefits can be garnished to satisfy a support obligation.

If parents live in different states, federal law (working alongside Missouri's version of the Uniform Interstate Family Support Act) requires other states to enforce a Missouri child support order and generally prevents another state from modifying it — Missouri typically keeps continuing jurisdiction over its own order unless narrow exceptions apply.

Unpaid child support also follows a parent into bankruptcy. Under federal bankruptcy law, child support is a "domestic support obligation" that cannot be discharged (wiped out) in bankruptcy, and it's paid ahead of most other unsecured debts. Property-settlement debts owed to an ex-spouse from a divorce decree are also generally treated as non-dischargeable.

Time-Sensitive: Updated Form 14 for 2026

Missouri adopted an updated Civil Procedure Form No. 14 and a revised Schedule of Basic Child Support Obligations, effective January 1, 2026. If your case involves an older calculation, a pending modification, or a Form 14 you completed before that date, confirm with your Missouri circuit court's family court clerk or the court's forms page that you're working from the current version — using an outdated schedule can produce the wrong presumed amount.

What You Can Do in Missouri

1. Get both parents' current income documentation together, since Form 14 requires combining both incomes to calculate the basic support obligation.
2. Confirm you're using the current Form 14 and Schedule from your circuit court or the Missouri courts website, especially since a new version took effect January 1, 2026.
3. Document the actual parenting-time schedule, including overnights, since that directly affects the Line 11 adjustment and any equal-custody adjustment.
4. If you believe support should change, calculate the guideline amount under current numbers first to see whether it differs from the existing order by twenty percent or more — that's the threshold Missouri treats as a substantial change.
5. File and serve any modification motion promptly, since a reduction can only apply to payments due after the other parent is personally served — not to support that already accrued.
6. If your case is still pending and no support is being paid, ask the court about a temporary support order rather than waiting for final judgment.

This article is general information about Missouri child support law, not legal advice for your situation — consult a licensed Missouri attorney or your local family court clerk about your specific case.