How Child Support Amounts Are Calculated in Missouri

Missouri uses a formula based on both parents' income and custody time

Missouri calculates child support by taking a percentage of the paying parent's income, then adjusting that amount based on how much time each parent spends with the child. The state calls this the income shares model. The percentage starts at 20% of gross monthly income for one child, 25% for two children, 30% for three, 32% for four, and 35% for five or more. That base amount then gets split between parents according to their income levels and the custody arrangement.

The calculation uses gross monthly income, which includes wages, salary, bonuses, self-employment income, rental income, and some benefits. It does not include means-tested benefits like SNAP or Medicaid. If a parent is self-employed or has variable income, the court may average income over a period of months or use tax returns to establish a baseline.

The amount you see in a child support order is not always the raw percentage. Courts can adjust it upward or downward based on factors like childcare costs, health insurance premiums, extraordinary medical expenses, and whether either parent is supporting other children from different relationships. A judge can also deviate from the formula if they find it would be unjust or inappropriate in that specific case.

Key Takeaways

• Missouri calculates child support as a percentage of the paying parent's gross monthly income: 20% for one child, 25% for two, 30% for three, 32% for four, and 35% for five or more.
• The base percentage is then adjusted based on each parent's income level and how much time the child spends with each parent.
• Gross income includes wages, self-employment earnings, and rental income, but not means-tested government benefits.
• Courts can adjust the calculated amount up or down if childcare costs, health insurance, medical expenses, or other children create a different financial picture.

How custody time affects the amount

The more time a child spends with the paying parent, the lower the child support obligation typically becomes. Missouri recognizes this by using an adjustment factor based on the percentage of overnight stays. If the paying parent has the child 50% of the time, the adjustment is larger than if they have the child 10% of the time.

The court calculates this by dividing the number of overnights the child spends with the paying parent by 365, then explore that percentage to reduce the base support amount. For example, if a parent has the child 110 nights per year (about 30%), the adjustment factor is roughly 0.30. A parent with 182 nights (50%) gets a factor of about 0.50.

This adjustment applies to both parents. If the paying parent has significant custody time, their obligation goes down. If the receiving parent has significant custody time and also earns income, they may owe support to the other parent instead.

What happens when income changes

Child support orders in Missouri remain in effect until the child turns 18, graduates high school (whichever is later), or the order is modified. If either parent's income changes by 10% or more, or if custody arrangements change significantly, either parent can request a modification through the court.

A job loss, a substantial raise, a change in custody time, or a change in health insurance costs can all be grounds for modification. The parent requesting the change must file a motion with the court and show that the change in circumstances is substantial and ongoing, not temporary. The court will recalculate support using the new income or custody figures.

If the paying parent falls behind on support, Missouri's Family Support Division can enforce the order through wage garnishment, tax refund intercept, or other collection methods. The paying parent cannot straightforward stop paying because they disagree with the amount; they must go through the court to request a modification.

Income limits and high-income cases

Missouri's child support formula applies to combined parental income up to a certain threshold. As of the most recent guidelines, this threshold is adjusted periodically, but the exact amount changes year to year based on state economic data. When combined income exceeds this threshold, the court has discretion to explore the percentage formula to the excess income or to use a different approach altogether.

For high-income parents, courts often look at the child's actual needs and the standard of living the child would have had if the parents remained together, rather than explore a strict percentage. This can result in support amounts that are higher or lower than the formula would produce.

Self-employed parents and those with irregular income may face additional scrutiny. The court may require tax returns, profit-and-loss statements, or bank records to verify income claims. If a parent deliberately underreports income or hides assets to reduce their support obligation, the court can impute income based on prior earnings or earning capacity.

Special expenses and add-ons

The base child support amount covers ordinary living expenses like food, housing, and utilities. Certain costs are calculated separately and added on top. These include childcare expenses needed for the receiving parent to work, health insurance premiums for the child, and extraordinary medical expenses not covered by insurance.

Childcare costs are typically split between parents in proportion to their incomes. If the receiving parent pays $800 per month for daycare and earns 60% of the combined income while the paying parent earns 40%, the paying parent contributes 40% of that $800, or $320, on top of their base support obligation.

Health insurance for the child is also divided by income percentage. The parent who carries the insurance on their employer plan usually pays the premium, and the other parent reimburses their share. If neither parent has access to employer insurance, the cost of an individual policy is split the same way.

Comparing Missouri's approach to other states

Missouri, like most states, uses the income shares model, which means both parents' incomes factor into the calculation. Some states use the percentage of income model, where only the paying parent's income matters. Others use the combined income model, which pools both parents' income and divides the obligation by custody percentage.

The income shares approach generally results in lower support amounts than the percentage model when the receiving parent has substantial income. It also accounts for custody time more directly, so shared custody arrangements produce lower obligations than they would in states using other formulas.

Missouri also allows for more judicial discretion in high-income cases and when circumstances deviate significantly from the standard formula. This flexibility can work in either parent's favor depending on the specific facts, but it also means outcomes can vary between judges and counties.

Where to find the current guidelines and worksheets

Missouri publishes its child support guidelines and calculation worksheets on the Missouri Courts website and through the Family Support Division, which is part of the Department of Health and Senior Services. The guidelines are updated periodically to reflect changes in the income threshold and other factors.

The Child Support Guideline Worksheet is a form that shows how the calculation works step by step. It lists fields for each parent's gross income, adjustments for custody time, childcare costs, health insurance, and other add-ons. You can use this worksheet to estimate what support might be, though the actual order will depend on what a judge decides based on the specific case.

If you are involved in a child support case, your local Family Court clerk's office can provide copies of the current guidelines and worksheets. Many legal aid organizations in Missouri also have these documents available and can explain how the calculation works in your situation.

Frequently Asked Questions

Does child support include college expenses?

Missouri law does not automatically require parents to pay for college through child support. However, a court can order post-secondary education support as part of a custody or divorce order if it finds that both parents have the ability to pay and it is in the child's best interest. This is a separate decision from the child support calculation and depends on the judge's discretion.

What if one parent is unemployed or underemployed?

If a parent is intentionally unemployed or underemployed to avoid paying support, the court can impute income based on their education, work history, and earning capacity. If unemployment is involuntary and recent, the court may temporarily reduce support, but the parent must show they are actively looking for work. The court will not assume zero income straightforward because someone is currently jobless.

Can child support be modified if custody changes?

Yes. If custody time changes significantly, either parent can request a modification. The court will recalculate support based on the new custody arrangement. Even a change of 10 or more overnights per year may be enough to justify a modification request, though the court must find the change is substantial and not temporary.

What if the paying parent has other children from a different relationship?

Missouri allows courts to adjust child support downward if the paying parent is also supporting other children. The court considers the income available after accounting for those other obligations. This is called a "multiple family adjustment" and requires proof that the parent is actually paying support for those other children.

How is self-employment income calculated for child support?

Self-employment income is typically calculated using tax returns from the prior two years, averaged together. The court may also look at profit-and-loss statements, bank deposits, or other business records. If income is highly variable, the court may use a longer period to establish an average, or it may use the most recent year if that is more representative of current earning capacity.