How to Win a Child Support Modification Case

Child support modification · St. Louis and across Missouri

This guide covers how these cases are proved and defended. For an overview of the legal test, the 20 percent rule and the choice between going to court or asking the state to review your order, see our child support modification lawyer page.

Start With the Judgment You Want to Change

Most modification cases are won or lost on what the existing judgment says. Pull the signed judgment and the Form 14 attached to it before anything else, and answer two questions.

Build Two Accurate Form 14s

Judges compare the worksheet behind the current order with a worksheet on today’s numbers. Errors in the new one can sink an otherwise strong case. In Buckallew v. Hall, a 2026 Western District case, a father’s 20 percent showing failed because his Form 14 still claimed the overnight credit for time he wasn’t actually using.

Count every overnight carefully, including holidays and vacations, and claim only the time you actually use. In In re Marriage of Bennett (W.D. 2026), the trial court used the mother’s worksheet with a 10 percent credit. The appeals court counted the holidays, spring breaks and vacation weeks in the parenting plan, raised the father’s credit to 15 percent and cut support from $1,954 to $1,766 a month. Our child support calculator runs the current 2026 Form 14, and our parenting time calculator counts every overnight in the year.

Watch the adjustment for children born after the existing order. Under the January 2026 Form 14 directions, neither parent gets the line 2c credit in a modification for a child born after the current order, with two exceptions. If the new worksheet would raise support, the court may give the paying parent that credit to soften the increase. If it would lower support, the court may give the receiving parent that credit to soften the decrease. Either way, the credit can’t reverse the direction of the change.

Prove the Change Is Substantial and Continuing

The court weighs all of both parents’ financial resources, including whether either parent’s expenses are shared by a spouse or partner, and the earning capacity of a parent who isn’t working. Evidence that typically matters includes these.

The whole picture decides these cases. In Reinhart v. Reinhart, a 2018 Eastern District case, support dropped from $1,500 to $288 a month even though the paying father earned more and could still pay. The mother’s income had grown from $79,500 to $183,000, her new husband contributed about $530 a month, child care costs had ended, the older child was in college and the father had an added overnight.

If You’re Asking to Lower Support

A lower income helps only if it is real, lasting and not your choice. Courts look hard at timing. In Cross v. Cross (W.D. 2010), a father resigned from his second full-time job less than two weeks before filing. His resignation letter said he had been “strongly advised” to quit “to ensure the chance of victory.” The court used his two-job income and raised his support.

In McKenna v. McKenna (W.D. 2025), an engineer who had averaged about $274,000 a year left his job around the time the mother filed, applied nowhere for nearly two years, and had his old income imputed.

An involuntary loss is different. In Metzger v. Franklin (S.D. 2016), a father lost his job of 13 years when his employer moved to Mexico and enrolled in retraining. The appeals court reversed an imputed income based on a year inflated by severance. Document every application and offer. Where earning capacity is disputed, a vocational exam can decide the case.

Keep paying the current order while the case is pending. In Whitton v. Whitton (W.D. 2025), a father fell about $28,500 behind and testified he expected a retroactive modification to give him credit against what he owed. The appeals court held that belief was not good cause, reversed a finding that he wasn’t in contempt, and held his new amount could reach back only to the service date of his Missouri motion.

If You’re Asking to Raise Support

Show the other parent’s current income, not just your own costs. Subpoena employment and business records if needed, and look for income that doesn’t appear on a pay stub, such as bonuses, a second job, business perks or a spouse who shares expenses. Pair that with the children’s actual needs now, including child care, medical costs, activities and school expenses.

Private school is its own question. If neither the judgment nor an agreement between the parents covers it, the parent asking to add tuition must show the school meets a particular educational need. In McKenna, the parents never agreed on a parochial high school, and evidence about the children’s faith and their success at their grade school was not enough. An order for the father to pay half of the high school tuition was reversed.

If You’re Defending a Motion to Modify

Check the other parent’s Form 14 line by line, especially income and overnights actually exercised. Ask whether the claimed change is lasting, whether the judgment anticipated it, whether an income drop was voluntary, and whether the old order was even the Form 14 amount. In McLaughlin, evidence that the father had leased a Mercedes, joined two country clubs and spent about $2,200 a month on vacations and recreation helped defeat his claim that he could no longer pay.

If your own circumstances have changed, consider a cross-motion, and note that a judge isn’t required to depart from the new Form 14 amount just because a factor would allow it. In Hereth v. Hereth (W.D. 2025), a mother’s estimated travel costs of about $1,875 a month likely could have justified lower support, but the judge didn’t have to lower it.

Timing Decides How Much You Win

A new amount can apply only to payments that come due after the other parent is personally served, under section 452.370.6. In Tolu v. Stientjes, a 2024 St. Louis County case, the Eastern District reversed a new support amount that started before service. Every month between a lasting change and service stays at the old amount.

When both parents file, the date of the winning parent’s own motion controls. In Klein v. Klein (W.D. 2015), the father filed first to end support, the mother filed her cross-motion a month later and won an increase, and the increase could reach back only to the date she filed, not to his earlier filing. A parent who expects to win an increase shouldn’t wait to respond to the other parent’s motion before filing their own.

What Happens Between Filing and the Hearing?

After service, both parents exchange financial information and usually file statements of income and expenses. Either side can use discovery to get records the other parent controls. Many cases settle once both Form 14s are on the table. A settlement still needs a judge’s approval and, if it departs from Form 14, a finding that the presumed amount is unjust or inappropriate.

At a hearing, the judge first decides whether a substantial and continuing change has been shown, then calculates the presumed amount on Form 14 and decides whether to depart from it. Bring the documents behind every number on your worksheet. Judges decide these cases on records, not recollection.

Mistakes That Lose Modification Cases

How Bardol Law Firm Helps

Bardol Law Firm handles family law and nothing else, in St. Louis County, St. Louis City, St. Charles County and Jefferson County. Every attorney at the firm has at least two years of family law experience. We prepare and defend modification cases. That means pulling the original Form 14, building the new one with real income and real overnights, getting the motion served quickly, and testing the other side’s numbers.

Child support from the state’s side. Our attorney Denise N. Gabel spent fourteen of her twenty years in practice with the Missouri Attorney General’s Office in Child Support Unit leadership, so she has seen these cases from the state’s side as well as the parents’.

You can start with a one-hour, one-on-one consultation with an attorney in our office for $300. The consultation fee is not credited toward a retainer. We return calls from potential clients as quickly as possible, and usually within minutes. Call 314.918.0100 or use our contact page.

Frequently Asked Questions

This page gives general information about Missouri law as of October 2026 and is not legal advice. Every case turns on its own facts.

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