In re Marriage of Lamb

Published: 11/29/2025 • 11 min read
By Jonathan D. Steele

Summary

Case Summary: In re Marriage of Lamb - The article outlines seven critical mistakes that can derail child support modification cases in Illinois, including treating pre-existing income sources as changed circumstances, filing without forensic financial evidence, social media missteps, incomplete financial disclosures, missing procedural deadlines, and deleting digital evidence. A key legal point highlighted is that under Section 510(a)(1) of the Illinois Marriage and Dissolution of Marriage Act, petitioners must prove a substantial change in circumstances that occurred *after* the original order was entered—as demonstrated in *In re Marriage of Lamb* (2025), where the modification was reversed because the petitioner's prior knowledge of her ex-spouse's compensation structure disqualified it as a "changed circumstance."

# 7 Child Support Modification Mistakes That Will decisively rebut Your Illinois Case**In 20 years of practicing family law in Illinois, I've watched these seven devastating mistakes unfold.** They cost clients custody time. They drain thousands in legal fees. They decisively rebut any leverage clients once held.The February 2025 ruling in *In re Marriage of Lamb* just delivered a brutal reminder. It showed exactly what happens when you get child support modification wrong.Rachel Lamb walked into Greene County court convinced she had a winning case. Her ex-husband's finances had improved. She believed this justified a child support modification. She walked out of the appellate process with nothing. Her entire case collapsed because of mistakes that experienced attorneys see every single day.**Here's the truth most people don't want to hear.** Most child support modification petitions in Illinois fail. But not because the law is unfair. They fail because petitioners sabotage themselves with preventable errors.I've litigated these cases across Cook County, DuPage, and Lake County. The pattern never changes. Those who treat Section 510(a)(1) of the Illinois Marriage and Dissolution of Marriage Act as a formality? They lose everything. Those who avoid these seven mistakes? They win.---

Mistake #1: Treating Pre-Existing Income Sources as "Changed Circumstances"

What It Looks Like: You knew your ex-spouse earned bonuses during your marriage. Now those bonuses are bigger. So you file for modification claiming their income "substantially changed."

Why People Make It: It seems logical. More money should mean more support, right? Friends and family reinforce this misconception. Google searches return generic advice. That advice ignores Illinois's specific evidentiary requirements.

Real Consequence: This exact mistake destroyed Rachel Lamb's case. The Fourth District Court delivered a devastating finding. Her awareness of Thad's compensation structure—including bonuses and rebates—before filing her February 2023 petition was fatal. Knowledge you possessed when signing the original agreement cannot be repackaged. It will never qualify as a "changed circumstance." Her modification was reversed entirely.

The Cost: Rachel invested approximately 18 months in litigation. Conservative estimates place her legal fees between $35,000 and $60,000. That money is gone forever. She remains bound by the original MSA terms. She receives zero additional support.

How to Avoid It:

Illinois Law: 750 ILCS 5/510(a)(1) requires proof of substantial change occurring AFTER the entry of the original order. The *Lamb* court emphasized this distinction with surgical precision.

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Mistake #2: Filing Without Forensic Financial Evidence

What It Looks Like: You heard through mutual friends that your ex bought a new boat. You saw vacation photos on Instagram. You file for modification based on these "obvious" signs of wealth. But you have zero financial documents to back it up.

Why People Make It: Lifestyle evidence feels compelling. It's visible. It's tangible. It makes you angry. But feelings don't survive cross-examination.

Real Consequence: A DuPage County petitioner in 2023 sought increased support. Her ex-husband's construction business had "expanded." Revenue had grown from $1.2 million to $2.1 million. The court denied modification anyway. Why? She failed to distinguish between gross revenue and actual owner compensation. No forensic accountant testified. No documentation established what the obligor actually took home.

The Cost: Legal fees exceeded $45,000 for the unsuccessful petition. The case was dismissed. She paid a portion of his attorney's fees on top of her own.

How to Avoid It:

Illinois Law: Under 750 ILCS 5/505(a)(3), courts examine actual income from all sources. But you must prove what that income is with admissible evidence. Assumptions won't cut it.

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Mistake #3: Posting About Your Case on Social Media

What It Looks Like: You vent on Facebook about your ex's "hidden money." You post photos of your new car to show you're "doing fine." You message friends about court dates and strategy through Instagram DMs.

Why People Make It: Social media feels private. Your account is "locked down." You're just talking to friends. You don't realize something critical. Every word, photo, and emoji is discoverable evidence. Opposing counsel is already screenshot-capturing everything.

Real Consequence: In a 2024 Cook County case, a mother sought primary custody. She posted weekend photos captioned "Finally free! Girls' night every Saturday!" The father's attorney introduced these posts as evidence. They argued she prioritized socializing over parenting time. Her request for increased parenting time was denied. The court questioned her judgment in the written order.

The Cost: Lost credibility with the judge. No amount of money can repair that damage. Reduced parenting time. A written finding that will follow her into any future modification attempts.

How to Avoid It:

Illinois Law: Illinois Supreme Court Rule 214 permits discovery of electronically stored information. This includes social media content. Privacy settings do not protect you from subpoenas.

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Mistake #4: Submitting Incomplete or Inaccurate Financial Affidavits

What It Looks Like: You "forget" to list your cryptocurrency holdings. You underreport freelance income because "it's not consistent." You omit your new spouse's contribution to household expenses.

Why People Make It: Financial affidavits are tedious. Some people genuinely forget accounts. Others strategically omit information hoping no one will notice. Both approaches are catastrophic.

Real Consequence: A Cook County obligor in 2024 failed to disclose cryptocurrency holdings. Those holdings had appreciated from $80,000 to $620,000 post-divorce. The petitioner's forensic accountant traced blockchain transactions. They found wallets the obligor controlled. The court didn't just grant the modification. It imposed $12,000 in sanctions for discovery abuse. It ordered ongoing disclosure of all cryptocurrency wallets.

The Cost: A $3,400/month support increase. PLUS $12,000 in attorney's fees awarded to the other side. PLUS ongoing court supervision of his finances. His attempted concealment cost him far more than honest disclosure ever would have.

How to Avoid It:

Illinois Law: 750 ILCS 5/501(a)(4) requires full financial disclosure. Courts have broad discretion to sanction parties who violate disclosure requirements under Illinois Supreme Court Rule 219.

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Mistake #5: Missing Filing Deadlines and Procedural Requirements

What It Looks Like: You file your modification petition in the wrong county. You miss the 30-day response deadline. You serve documents by regular mail when certified mail was required. You assume the court will "understand" your delay.

Why People Make It: Procedural rules seem like technicalities. Self-represented litigants often don't know the rules exist. Even attorneys sometimes miscalculate deadlines. Some assume opposing counsel won't enforce them.

Real Consequence: A Will County petitioner in 2024 filed her modification motion 33 days after receiving the obligor's financial disclosure. That was three days past the deadline for filing a responsive pleading. The court struck her motion. She had to refile. She lost four months. She incurred an additional $8,000 in fees to restart the process.

The Cost: $8,000 in additional legal fees. Four months of delay. Lost momentum and credibility with the court.

How to Avoid It:

Illinois Law: Illinois Supreme Court Rule 181 governs service requirements. Rule 183 addresses deadline extensions. Venue for modification is controlled by 750 ILCS 5/510.

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Mistake #6: Deleting Text Messages and Digital Evidence

What It Looks Like: You delete angry text messages you sent your ex. You clear your browser history. You "clean up" your email before litigation. You think destroying evidence protects you.

Why People Make It: Panic. Embarrassment. The mistaken belief that if evidence doesn't exist, it can't hurt you. But digital evidence rarely disappears completely. And the act of deletion creates its own legal problems.

Real Consequence: A Lake County father deleted text messages. Those messages showed he had agreed to let the mother have extra parenting time during a school break. When the mother produced her copies of those same texts, the court drew an adverse inference. It assumed the deleted messages contained information harmful to the father. His credibility was destroyed for the remainder of the case.

The Cost: An adverse inference instruction to the court. Sanctions for spoliation of evidence. Complete loss of credibility that affected every subsequent ruling in his case.

How to Avoid It:

Illinois Law: Spoliation of evidence can result

References

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