In Illinois there are two types of child support. The first is the typical support paid by the noncustodial parent to the custodial parent. The second is support paid to the state for reimbursement for assistance to the custodial parent by the State of Illinois. This type of assistance can include Temporary Assistance for Needy Families (TANF), SNAP benefits, and/or medical assistance.

For child support owed to the custodial parent, it is up to the trial court to make any changes to the arrangement. Changing a child support order requires a petition for modification to be filed with the court that must show a “substantial change in circumstances”. 750 ILCS 5/510(a)(1) (West 2021). A substantial change in circumstances that may justify a reduction in child support can include serious illness that has impacted the ability to work, involuntary unemployment, or incarceration. Voluntary unemployment, which includes quitting a job does not justify a reduction in child support.

While courts consider incarceration a form on unemployment, pursuant to 45 CFR § 302.56(c)(3) states may not treat incarceration as a form of voluntary unemployment. Prior to that federal regulation, Illinois courts have long held that incarceration is not a form of voluntary unemployment and therefore may justify a reduction in child support. In re Marriage of Burbridge, 317 Ill.App.3d 190, 193, 738 N.E.2d 979, 982 (2000).  If support modification is sought due to incarceration, the court considers all relevant factors, including: (1) the assets of the incarcerated parent, (2) the length of incarceration, (3) the reason for incarceration, and (4) the potential for work release. People ex rel. Meyer v. Nein, 209 Ill.App.3d 1087, 154 Ill.Dec. 436, 568 N.E.2d 436 (1991). Though this is not applicable if the parent is incarcerated for a failure to pay child support or for offenses against the child or custodial parent.

However, a change in a child support order only affects installments “subsequent to due notice of the petition for modification” 750 ILCS 5/510(a)(1998). This means that a modification can only be retroactive to the date of filing, so any accrued child support arrears or debt must still be paid.