Post-Decree Motions in Illinois Family Court: Modify, Enforce or Vacate

The short answer

Start by naming the problem. If circumstances have changed, you ask to modify the order. If the other side is not following it, you ask the court to enforce it. If the judgment itself was entered in error, you ask to vacate or correct it. Each is filed in the original case, with notice to the other party, and each has its own proof and time limits.

What post-decree means in Cook County

"Decree" is the everyday word for the judgment that ends a divorce, legal separation or parentage case. Anything filed after that judgment is post-decree, or post-judgment. Under 750 ILCS 5/511, a divorce judgment may be enforced or modified by petition. The petition is filed in the judicial circuit where the judgment was entered or last modified, with notice mailed to the other party's last known address or by summons.

Under Rule 13.3(c)(i) in Part 13 of the Rules of the Circuit Court of Cook County, a post-judgment motion from a team calendar goes to that team's post-decree judge, and one from an individual calendar returns to that calendar. Rule 13.6(b) says post-judgment matters are heard by the judge or team that entered the judgment, with limited exceptions.

Modification: support, maintenance and parenting

Child support

Under 750 ILCS 5/510(a), child support may be modified on a showing of a substantial change in circumstances. There is a second route in some cases. If the order differs from the guideline amount by at least 20 percent and at least $10 a month, it can be changed without that showing, unless the gap comes from an approved deviation whose reasons have not changed. This route applies only to cases getting child support services from the Illinois Department of Healthcare and Family Services, and only 36 months after the order was entered or last changed. A need to cover the child's health care is another ground. Most important, a change applies only to payments that come due after the other side gets notice of the filing. Waiting costs money. See our child support enforcement guide.

Maintenance

Section 510(a-5) allows maintenance to be modified or terminated only on a substantial change in circumstances. The court weighs the Section 504 factors and those in Section 510, such as good-faith job changes, the receiving spouse's efforts to become self-supporting and income changes. Under Section 510(c), unless a written agreement in the judgment says otherwise, future maintenance ends on the death of either party, the remarriage of the receiving spouse, or the receiving spouse's cohabitation with another person on a resident, continuing conjugal basis.

Parenting time and decision-making

Section 610.5 of the Act controls. Parenting time may be modified at any time on a showing of changed circumstances that makes a change necessary for the child's best interests. Decision-making is different. Unless the parents agree, a motion to change it cannot be filed within two years of the order. The exception is when the court allows it based on affidavits showing reason to believe the child's present environment may seriously endanger the child's mental, moral or physical health, or significantly impair the child's emotional development. If the change serves the child's best interests, the court can also approve minor modifications, or changes that reflect an arrangement in place without objection for six months, without proof of changed circumstances. In Cook County, Rule 13.4(e) makes mediation mandatory for contested modification of parental responsibilities unless an impediment exists, and Rule 13.4(f) requires an approved parenting education program in post-decree modification and relocation cases unless excused for good cause. See also our guide on when to modify a parenting plan.

Property division

Property terms are much harder to change. Section 510(b) says provisions for property disposition may not be revoked or modified unless the court finds conditions that justify reopening a judgment under Illinois law.

Enforcement: petitions for rule and contempt

When the other side is not following the judgment, the usual tool is a petition for rule to show cause. Cook County Rule 13.8(a) requires the request to be in writing, to identify the specific order or provision violated, and to be properly served, with the judgment or order attached or presented to the court. Our full guide to the petition for rule in Cook County walks through the hearing and purge.

Two statutes support enforcement. Under 750 ILCS 5/508(b), when the court finds that noncompliance was without compelling cause or justification, it must order the violating party to pay the prevailing party's reasonable attorney fees and costs. Under Section 510(f), a petition to modify child support or parenting time does not delay child support enforcement litigation, such as a petition for rule.

Vacating or correcting a judgment

Two statutes cover challenges to the judgment itself:

• Within 30 days. Under 735 ILCS 5/2-1203, in a case tried without a jury, a party may move for rehearing, retrial, modification, vacating the judgment or other relief within 30 days after entry, or within any extension the court allows in that period. In Cook County, Rule 13.6(c) sends these motions back to the judge who entered the judgment unless otherwise ordered.
• After 30 days. Under 735 ILCS 5/2-1401, relief from a final judgment requires a petition filed in the same case. It must be supported by an affidavit or other showing for facts outside the record. The petition generally must be filed within two years after the judgment. Time is not counted while the person was under a legal disability or duress, or while the ground for relief was fraudulently concealed. Filing the petition does not suspend the judgment.

Our guide to motions to vacate in Illinois family law cases explains both routes in more detail.

Relocation and parenting time abuse

Under Section 609.2, a parent with the majority of parenting time, or either parent with equal parenting time, may seek to relocate with a child (a move that meets the Section 600(g) definition). The parent must give written notice at least 60 days before the move, unless that is impracticable or the court orders otherwise, and file a copy with the Clerk. If the other parent signs the notice and it is filed, the move is allowed without more court action. If the other parent objects or will not sign, the relocating parent must file a petition, and the court applies the statutory factors. See our child relocation guide.

When a parent denies or interferes with court-ordered parenting time, Section 607.5 provides an expedited enforcement petition. It must state the current parenting terms, the dates and nature of the violation, and that a reasonable attempt was made to resolve the dispute. On a finding by a preponderance of the evidence, the court may order makeup time, counseling, a parenting class, a bond, a civil fine or other relief, and, except for good cause, must order the noncomplying parent to pay the other parent's reasonable fees and costs.

Filing and service for a post-decree motion in Cook County

1. Gather the judgment and every later order. Rule 13.6(f) requires the moving party to have the pending motion, the notice of motion, the judgment with its agreements and the most recent order available to the judge at each court date.
2. Pick the right request and cite it. Rule 13.4(a) requires a written motion or verified petition, titled with an accurate description of the main relief sought, that states the statute or authority relied on.
3. Exchange financial affidavits when money is at issue. Rule 13.3.1(b) requires a financial affidavit, with proof of income under Rule 13.3.2, in post-judgment proceedings on maintenance, child support, educational expenses or attorney fees, unless a party objects in writing and shows good cause.
4. E-file in the original case. File through eFileIL, using Odyssey eFileIL or another approved provider. The Clerk's miscellaneous fee schedule, revised October 28, 2025 and viewed October 18, 2026, lists a $0.00 fee for petitions to modify, terminate or enforce a child support or spousal support order; other post-judgment filings can carry fees. Confirm current amounts on the Clerk's Domestic Relations fee schedule.
5. Serve correctly. Section 511(a) calls for notice mailed to the other party's last known address, or summons, so do not send it only to the divorce lawyer. After the other party appears, later documents go to their lawyer of record, if any, under Supreme Court Rule 11. Hearing notices must meet Cook County Circuit Court Rule 2.1.
6. Prepare for court. Bring copies, a timeline, your evidence and a proposed order. Hearings may be in person or by Zoom, as the judge directs.

What the other side can do

• File a written response, or a counter-petition asking for different relief.
• Dispute that circumstances changed substantially. Under Section 510(a), the other side can argue an event was foreseeable only if the order or agreement expressly specified it.
• In enforcement cases, show compelling cause or an inability to comply.
• Ask for fees under Section 610.5(f) if a modification case is vexatious or harassing.
• Challenge a petition to vacate as late or as lacking the required supporting affidavit.

Common mistakes to avoid

• Waiting to file a support modification. Changes generally reach back only to installments due after notice of the filing.
• Stopping payments or changing schedules on your own. Self-help can lead to enforcement and fee awards against you.
• Choosing contempt when the order is unclear. A motion to clarify or modify may fit better.
• Missing the 30-day window for a motion under Section 2-1203.
• Filing a decision-making modification within two years without the required endangerment affidavits.
• Skipping the parenting class or mediation required for contested parenting modifications in Cook County.

How Chicago Family Attorneys can help

Chicago Family Attorneys, at 53 W. Jackson Blvd., Suite 752, in the Chicago Loop, handles post-decree matters in Cook, DuPage, Will and Lake Counties, including enforcing family court orders and modifying parenting orders.

• Limited-scope drafting. Drafting a motion to modify parenting time, or a response to a post-decree motion, for you to file is a flat fee starting at $500.
• One hearing appearance. Appearing for you at a specific hearing is a flat fee starting at $1,200. See limited-scope fees.
• Full representation for a modification. An initial payment of $1,500 to $2,500, then $500 to $650 per month beginning 30 days after the initial payment while representation remains active. See parenting order modification fees.
• Enforcement. Enforcing an existing order is billed differently; see our court order enforcement fees.

Your fee and scope are confirmed in writing before you engage the firm. Bring your judgment, later orders and a dated list of events to the consultation; our 25 questions for your divorce consultation can help you prepare.