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Illinois Child Support Modification Explained | What is a "Substantial Change in Circumstances" For Modifying Child Support?

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Article written by Attorney Kevin O'Flaherty
Updated on
October 28, 2019

In this article we will discuss both the process for modifying child support obligations in Illinois and what constitutes a "substantial change in circumstances" that would allow child support to be modified.  For some foundational information, check out our articles: Illinois Child Support Law Explained and Recent changes to Illinois Child Support Law.

When Can Child Support Be Modified in Illinois? 

In Illinois, a temporary child support order that has been entered while a child support proceeding is pending may be modified any time before the entry of a final judgment.  Child support that has been established by a final judgment may be modified at any time from the entry of the order until the termination of the obligor parent's obligation to pay child support under the order.  

However, although child support may be modified at any time, a "substantial change in circumstances" must be demonstrated in order of the child support obligation to be modified.

Can a Child Support Modification Take Effect Retroactively?

If you file a petition to modify a child support order based on "substantial change in circumstances" the child support obligation in question can be modified retroactively to the filing date of the petition, but can not have an earlier effective date.

Will I be able to Modify My Child Support Obligation Based on the New Illinois Child Support Law that went into Effect on July 1, 2017?

Even though Illinois Child Support laws changed on July 1, 2017, leading to a different model for calculation of child support for child support orders entered after that date, this change in the law will not alone constitute a basis for the modification of existing child support obligations entered before July 1, 2017.  If your child support order was entered prior to July 1, 2017, you will still need to demonstrate a "substantial change in circumstances" other than the passage of the new law in order to have your child support obligation modified.  However, if you are able to demonstrate a "substantial change of circumstances" after July 1, 2017, any modification of your child support will be calculated according to the new Illinois child support law. 

How to modify illinois child support orders

How to Modify Child Support in Illinois

Illinois child support obligations can only be modified by filing a petition for increase or decrease in child support with the court that has jurisdiction over your case.  The petition should state the basis for the request for modification as well as a "prayer for relief" explaining the change in child support obligation that you are requesting from the court.

Because you are seeking modification of an existing order, you do not need to serve the petition by sheriff.  You can serve notice of the petition by mail at the responding party's last known address. Note that if the petition seeks other action by the court other than the modification of child support, such as a change in the allocation of parental time and responsibility, the petition must be served by certified mail 30 days prior to the date of the hearing.

If you are seeking child support modification after a final judgment has been entered in your case, the notice must be delivered to the responding party, as opposed to his or her attorney, because the attorney's representation is deemed to have ended at the entry of the final order.  

You should note that you cannot use self help to modify child support in Illinois.  If the other party fails to comply with visitation rights, you are not entitled to suspend your child support payments without obtaining an order from the court. 

Vested Child Support Obligations Cannot be Modified

A "vested" child support obligation is a child support payment that has already become due according to the terms of the judgment.  Although child support obligations that are not yet due can be modified at any time upon a showing of a "substantial change in circumstances, vested child support obligations can only be modified with the consent of the other party.  

Do I Have to Pay Child Support While an Appeal is Pending?

If you are appealing the final order in your child support case, you are still required to pay child support according to the terms of that order while the appeal is pending.  However, you can request the court that entered the order to modify your child support obligations during the appeal process based on a showing of "substantial change in circumstances.

Reasons for Modification of Child Support in Illinois

The court has discretion to modify child support obligations based on either a substantial change of circumstances, upon a showing that the modification is necessary to provide for the healthcare needs of the child, or upon a showing of a substantial deviation between the child support obligation and the guidelines set forth by the Illinois Marriage and Dissolution of Marriage Act ("the IMDMA"). 

Modification of Child Support Based on Deviation from Guidelines

Child support modifications can be modified without a showing of a substantial change in circumstances if the petitioner can show that the obligor's child support obligations differ from the guidelines set forth in the IMDMA by more than 20%, but no less than $10.00 per month, unless the court that entered the existing order intentionally deviated from the amounts shown in the guidelines.  However, this option is only available to individuals who are receiving child support enforcement services from the Illinois Department of Health and Human Services and whose child support order was entered more than 36 months prior to seeking modification. 

Modification of Child Support Based on Substantial Change in Circumstances

Modification of Child Support Based on Substantial Change in Circumstances

The most common reason for the court to award a modification of child support is the petitioner's showing of a "substantial change of circumstances" occurring after the entry of the previous order.  The court has broad discretion to determine whether a substantial change in circumstances has occurred. The test is whether there has been a change of circumstances of any nature that would justify equitable action by the court for the best interests of the children while appropriately considering the rights and interests of the parents.  Courts have defined what qualifies as a "substantial change in circumstances" through precedent established by case law. 

  • Inflation & Cost of Living Increases: Inflation alone will not constitute a substantial change in circumstances.  In order to have child support increased based on an increased cost of living, the petitioner must demonstrate specific evidence of increased expenses, as opposed to general statistics. 
  • Increased Needs of the Children:  Increased needs of the children can lead to an increase in child support obligations.  However, the children's increased needs are balanced against each parent's relative ability to provide for such needs.  Courts use a "substantial imbalance" test to determine whether there is a "substantial imbalance" between the children's needs and the ability of the parents' ability to pay, as opposed to automatically increasing child support based on increased needs of the children.  Courts first assess to what extent the children's needs have increased, and, if they have, courts next analyze the financial situation of each parent to determine which party is in a better position to provide for the increased needs of the children. 
  • Increased Financial Ability of the Obligor Parent: Even if the children's needs have not increased, an improvement in the financial position of the obligor parent may lead to an increase in child support.  This can occur through an increase in income, decrease in other financial obligations, or the reduction or termination of maintenance payments.  In conducting this analysis, courts will weigh the standard of living that the children would have enjoyed had the marriage continued. 
  • Decreased Financial Ability of the Obligor Parent: A decrease in the financial ability of the obligor parent to pay constitutes a substantial change in circumstances for the purpose of modifying child support, whether this occurred from a lowering of income, loss of employment, or increased expenses.  A voluntary change of employment made by the obligor parent resulting in reduced income may reduce child support of the change was made in "good faith."  "Good faith" means that the obligor parent's motive in changing employment was something other than reducing his or her child support obligation.  Courts have found that an obligor parent leaving his or her job to return to college full time can reduce child support of if the obligation was made in good faith.  However, early retirement has not been found to be a sufficient change in circumstances to reduce child support.  
  • Increased or Decreased Financial Ability of the Recipient Parent:  A change in the economic circumstances of the parent receiving child support can be the basis for an increase or decrease in the other parent's child support obligations. 
  • Remarriage of Either Parent:  The remarriage of either parent will not alone constitute a change in circumstances sufficient to modify child support.  Instead, the court will weigh any increased in financial obligations, the income of the new spouse, and the financial situation of the new family. 
  • Change in Allocation of Parenting Time and Custody:  A change in relative parenting responsibilities constitutes a substantial change in circumstances, the more time that the obligor parent has custody of the child, the more likely his or her child support obligations will be reduced. 
  • Emancipation of a Child:  Emancipation of a child occurs when the child has voluntarily left the parent's home and assumed responsibility for his or her own care, or when the child reaches the age of majority (unless otherwise agreed or ordered by the court).  The emancipation of one of children will serve to reduce the obligor's child support obligation.  However, unless the child is the only child for whom child support is being paid and the emancipation occurs by reason of the child reaching the age of majority, the child support obligation still requires a court order for reduction.  
  • Resources of the Child:  An increase in the financial resources of the child, such as receipt of a large inheritance, can serve to reduce the obligor parent's child support obligation.  
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Illinois Child Support Modification Explained | What is a "Substantial Change in Circumstances" For Modifying Child Support?

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