Missouri does not publish a flat dollar figure for one child. Instead, the amount of child support for one child in Missouri is calculated by running both parents’ incomes through a state worksheet called Form 14, which produces a presumed monthly obligation based on combined income, work-related childcare, health insurance premiums, and the number of overnights the child spends with each parent. A revised Form 14 took effect on January 1, 2026, so any calculation should use the current worksheet from the Missouri Courts website.
What Form 14 Actually Calculates
Missouri uses the Income Shares Model. The idea is that a child should receive roughly the same share of parental income they would have received if the parents lived together, and both parents contribute in proportion to what they earn. Missouri Supreme Court Rule 88.01 requires every child support case to start with Form 14, and the number it produces is presumed correct unless a parent proves it would be unjust or inappropriate.1Cornell Law School. 13 CSR 40-102.010 – Child Support Obligation Guidelines2Missouri Revisor of Statutes. RSMo 452.340 – Child Support, How Determined
The worksheet follows a set sequence. Each parent’s gross monthly income is calculated, the two figures are combined, and that combined income is matched against the state’s Schedule of Basic Child Support Obligations. The schedule assigns a base monthly amount for one child at that income level. Each parent owes a share of that base proportional to their contribution to combined income: if you earn 60 percent of the total, you owe 60 percent of the base. The parent without primary custody pays their share to the custodial parent.
Income That Counts
Gross monthly income is more than wages. Missouri includes salary, commissions, overtime, bonuses, Social Security, veterans’ benefits, workers’ compensation, dividends, interest, rent, net self-employment earnings, pensions, retirement distributions, severance, and alimony received from a prior marriage. If you already pay court-ordered support for other children, that payment is subtracted before the two incomes are combined.
When a Parent Is Not Working
A parent cannot shrink the obligation by quitting a job or taking a deliberate pay cut. If a court finds that a parent is voluntarily unemployed or underemployed to avoid support, it can impute income based on what the parent could earn.3Missouri Revisor of Statutes. RSMo 452.330 – Maintenance and Support Motive is the question. A parent who was laid off and is actively looking for comparable work is treated differently from one who walked away from a well-paid position without good reason.
Costs Added on Top of the Base Amount
The schedule figure is only the starting point. Form 14 adds three categories of real-world costs, and these can push the final number well above the base, especially when the child is young:
- Work-related childcare: daycare, after-school care, or summer programs needed so a parent can work or attend school.
- Health insurance premiums: the cost of covering the child on a parent’s plan. The parent who pays the premium gets credit for it.
- Uninsured extraordinary medical expenses: out-of-pocket medical, dental, vision, or psychological costs the insurance does not cover.
These add-ons are totaled and divided between the parents in the same income proportion used for the base amount.
The Overnight Credit That Changes the Math
Line 11 of Form 14 reduces the paying parent’s share based on how many overnights the child spends in that parent’s home each year. A parent who has the child for a meaningful stretch of nights is already covering food, utilities, and daily expenses during that time, and the worksheet accounts for it on a tiered scale:
- 36 to 72 overnights: 6 to 10 percent reduction
- 73 to 91 overnights: 11 to 20 percent reduction
- 92 to 109 overnights: 21 to 25 percent reduction
- 110 or more overnights: up to a 50 percent reduction
The reduction comes off the paying parent’s proportional share of the base obligation. For near-equal parenting schedules, the credit can cut the monthly payment in half. The overnight count comes from the court-approved parenting plan, not from informal swaps between the parents.
When the Court Orders a Different Amount
Form 14’s result is presumed correct, but either parent can ask the court to deviate if the number would be unjust or inappropriate given the family’s situation. A deviation requires a written finding from the court explaining why.2Missouri Revisor of Statutes. RSMo 452.340 – Child Support, How Determined Judges weigh:
- The child’s financial needs and resources
- Each parent’s financial resources and needs
- The standard of living the child would have had if the parents remained together
- The child’s physical, emotional, and educational needs
- The custody arrangement and expenses tied to visitation
- Reasonable work-related childcare costs
Deviations are not routine. They tend to appear when a child has significant medical needs the schedule cannot absorb, or when the calculated amount would leave the paying parent without enough to cover basic living expenses.
How Long the Obligation Runs
Support for one child in Missouri generally ends at age 18. If the child is still finishing high school or an equivalent program at that point, support continues until the program ends or the child turns 21, whichever is sooner.2Missouri Revisor of Statutes. RSMo 452.340 – Child Support, How Determined Support also ends earlier if the child marries, enters active military duty, becomes self-supporting after the custodial parent releases parental control, or dies. For a child who is physically or mentally unable to support themselves, the obligation can extend past 21, but only if the order itself says so.
There is also a partial-abatement rule for extended visits. If the child stays with the paying parent for more than 30 consecutive days, the monthly obligation reduces in whole or in part for that period.2Missouri Revisor of Statutes. RSMo 452.340 – Child Support, How Determined
Changing the Amount After It Is Set
Either parent can ask the court to modify an existing support order when there has been a substantial and continuing change in circumstances that makes the current amount unreasonable.4Missouri Revisor of Statutes. RSMo 452.370 – Modification of Maintenance or Support Typical triggers are a job loss, a significant raise or pay cut, a change in the child’s needs, or a real shift in the parenting schedule.
Missouri gives a concrete threshold. If recalculating the obligation under the current guidelines would change the amount by 20 percent or more compared with the existing order, that difference alone creates a presumption that modification is warranted.4Missouri Revisor of Statutes. RSMo 452.370 – Modification of Maintenance or Support When reviewing a modification request, the court looks at all financial resources of both parents, including the earning capacity of a parent who is not currently employed and the extent to which a new partner shares a parent’s living expenses.
Because every piece of Form 14 moves with the facts (income, childcare, insurance, overnights) two Missouri families with the same combined income can end up with very different monthly numbers. The only reliable way to know what support for one child will be in your case is to run the current Form 14 with accurate figures for all four inputs.