Can I Modify Child Support if My Ex Earns More Money?

Life after divorce or separation doesn’t stay the same for long. Jobs change, incomes rise or fall, and expenses for raising children often increase. One common question parents ask is: “Can I request a child support modification if my ex earns more money?” In many cases, yes—Illinois law allows child support to be modified when there’s been a substantial change in circumstances. A significant raise in your ex’s income might qualify. But it’s not automatic, and the court will evaluate multiple factors.

This post walks you through the rules around modifying child support in Illinois, when a raise or increase in income might justify a change, and how to begin the process.

How Child Support Works in Illinois

Illinois uses an “income shares” model to determine child support. This means the court considers both parents’ incomes, the number of overnights each parent has with the child (i.e., parenting time), and the basic costs of raising children based on state guidelines. See 750 ILCS 5/505(a). Once child support is set by court order, it remains in effect until it is modified—either by agreement or through a motion filed with the court. “[P]rovisions pertaining to child support may not be made nonmodifiable.” In re Marriage of Singleteary, 293 Ill. App. 3d 25, 34 (Ill. App. Ct. 1997).

What Counts as a “Substantial Change in Circumstances”?

Under 750 ILCS 5/510(a)(1), a party can request a modification to child support if there has been a substantial change in circumstances since the last order. This can include:

• A significant increase or decrease in either parent’s income. See e.g., In re Marriage of Knight, 2024 WL 5230755 (Ill.App. 1 Dist.).
• A change in employment. In re Marriage of Connelly, 438 Ill. Dec. 188, 194 (Ill. App. Ct. 2020.
• A shift in parenting time or custody. 750 ILCS 5/505(a)(1)(F)
• Increased needs of the child (e.g., medical, educational). 750 ILCS 5/505(a)(1)(E)
• One parent having another child. 750 ILCS 5/505(a)(3)(F)

So, if your ex receives a notable and ongoing raise, or otherwise earns a substantially higher amount, that may qualify as a substantial change, making them potentially responsible for a higher share of the financial support.

When a Raise Justifies a Modification

A raise can justify a change in support, but Illinois courts don’t respond to every small change in income. Here’s what matters:

1. How Significant Is the Raise?

If your ex gets a modest annual cost-of-living adjustment, it probably won’t trigger a modification. But if they receive a substantial raise or promotion that materially affects their financial situation, that could meet the threshold. In re Marriage of Connelly, 438 Ill. Dec. 188, 194 (Ill. App. Ct. 2020).

2. Is It Permanent or Temporary?

A one-time bonus or temporary overtime bump is unlikely to move the needle. The court is more likely to consider long-term or permanent increases, such as a promotion or a new job with a significantly higher salary, unless the temporary change constitutes a substantial change in circumstances. See 750 ILCS 5/510(a).

3. How Long Since the Last Order?

Even if the raise is modest, a modification may be appropriate if it’s been several years since the last support order and other financial circumstances have changed. 750 ILCS 5/510(a).

What If My Ex Has Family Money?

Courts don’t only look at each parent’s employment income – they use income from all sources. 750 ILCS 5/505(a)(3)(A). If your ex inherits money or benefits from a trust fund, that may be counted as income for child support purposes. See Knight, 2024 WL 5230755.

Case Study: In re Marriage of Knight (2024)

In this case, Mother filed a motion to increase child support after Father’s income skyrocketed, thanks to some very generous family trusts. These weren’t new trusts either—Father had been the beneficiary all along, and per their prenuptial agreement, the trusts were considered his nonmarital property. Still, his lifestyle took a major turn toward luxury, while the kids—living with Mother—weren’t enjoying the same upgrades.

The couple had previously negotiated a Marital Settlement Agreement (MSA) through a cooperative law process. It included a monthly child support payment of $10,000, deviating from standard guidelines based on their then-current incomes. The MSA also locked in non-modifiable spousal maintenance of $4,000/month and laid out income ranges for both parties.

Father claimed the Mother’s motion to modify support was just a way for her to live more lavishly—something he thought they had contractually avoided. But the appellate court had a different take:

• Standard of Living Matters: The court emphasized that kids shouldn’t have to experience a “bare minimum” lifestyle with one parent while the other is living in luxury. The focus should be on the standard of living the children would have enjoyed had the marriage stayed intact.
• Trust Income Counts: Even though the trust money was nonmarital under the prenup, the income derived from those trusts can still be counted as part of Father’s income for child support purposes.
• Substantial Change in Circumstances: The appellate court rejected the idea that future trust income was “expected” or “contemplated” in the original MSA. Since Father’s current income far exceeded the agreed-upon income range, this amounted to a substantial change justifying modification.
• Not Just a Needs Test: The trial court made the mistake of focusing too much on a “needs-based” analysis. That’s not enough when a deviation from guideline support is at stake. The law requires courts to weigh factors like the children’s hypothetical standard of living had the marriage not ended.

This case demonstrates the general rule for child support cases: Courts look at total income, not just what’s titled “marital.” And if there’s a stark lifestyle contrast between the parents, it can trigger a reevaluation. The focus is the child’s well-being, not preserving one parent’s budgetary comfort.

Final Thoughts

Yes, you can modify child support if your ex earns significantly more – even if that income is from nonmarital trust funds – but only if that raise results in a substantial change in circumstances that materially affects the fairness of the current order. If you’re not sure whether the raise qualifies, it’s a good idea to speak with a family law attorney.

Have questions about modifying child support in Illinois? Contact O. Long Law, LLC today to schedule a consultation with an experienced family law attorney who can evaluate your case and guide you through the process.