The significance of this finding is that child support may be modified if the court finds that a substantial change in circumstances has occurred after the court's previous child support order. See In re Marriage of Adams, 348 Ill. App. 3d 340, 343 (2004).¶ 24 The court rejected Katherine's contention that the April 2013 amended joint parenting agreement did not address child support. It highlighted the provision which read, "All other provisions of the September 26, 2005, Order not expressly modified herein shall remain in full force and effect and stand as entered."

A court has "the authority to compel [a party] to pay child support at a level commensurate with their earning potential" and "may impute additional income to a noncustodial parent who is voluntarily underemployed." In re Marriage of Adams, 348 Ill. App. 3d 340, 344 (2004). Motions to modify child support are decided on the individual facts and circumstances of each case.

¶ 65 It is well established that courts have the authority to compel parties to pay support at a level commensurate with their earning potential. In re Marriage of Adams, 348 Ill. App. 3d 340, 344 (2004). "[I]f a court finds that a party is not making a good-faith effort to earn sufficient income, the court may set or continue that party's support obligation at a higher level appropriate to the party's skills and experience."

In re Marriage of Heil, 233 Ill. App. 3d at 894-95, 599 N.E.2d at 173. See also In re Marriage of Adams, 348 Ill. App. 3d 340, 343, 809 N.E.2d 246, 248 (2004); In re Marriage of Davis, 287 Ill. App. 3d at 851, 679 N.E.2d at 114; People ex rel. Stokely v. Goodenow, 221 Ill. App. 3d 802, 805, 583 N.E.2d 102, 104 (1991). Admittedly, there is a large disparity between the prior child support order and the current amount calculated as 20% of Father's income in this instance, but the earlier amount was set by agreement of the parties.

Illinois appellate courts have developed three primary factors to consider in determining when it is proper to impute income to a noncustodial parent. In order to impute income, a court must find that one of the following factors applies: (1) the payor is voluntarily unemployed ( In re Marriage of Adams, 348 Ill. App. 3d 340 (2004)); (2) the payor is attempting to evade a support obligation ( Sweet, 316 Ill. App. 3d 101); or (3) the payor has unreasonably failed to take advantage of an employment opportunity ( In re Marriage of Hubbs, 363 Ill. App. 3d 696 (2006)). If none of these factors are in evidence, the court may not impute income to the noncustodial parent. The determination of net income is reviewed under an abuse of discretion standard.

"[C]ourts have the authority to compel parties to pay child support at a level commensurate with their earning potential." In re Marriage of Adams, 348 Ill. App. 3d 340, 344, 809 N.E.2d 246, 249 (2004). "A court may impute additional income to a noncustodial parent who is voluntarily underemployed."

" '[C]ourts have the authority to compel parties to pay child support at a level commensurate with their earning potential' " and " 'may impute additional income to a noncustodial parent who is voluntarily underemployed.' " Deike, 381 Ill. App. 3d at 631 (quoting In re Marriage of Adams, 348 Ill. App. 3d 340, 344 (2004). ¶ 42 The record in this case supports the circuit court's finding that Scot was underemployed.

We also agree with Constantin's argument that there is a presumption that a child's needs increase as they grow older and the cost of living rises. See In re Marriage of Adams, 348 Ill. App. 3d 340, 343 (2004); In re Marriage of Pylawka, 277 Ill. App. 3d at 731. Accordingly, the trial court was incorrect in stating that it did not receive sufficient evidence to determine whether a duty of support existed in the first place. ¶ 61 Monica largely does not contest these points (see supra ¶¶ 52-53), instead arguing that the trial court could not determine an amount of child support without evidence pertaining to the factors under section 505.

We will not disturb a court's ruling on a petition to modify child support absent an abuse of discretion. In re Marriage of Adams, 348 Ill. App. 3d 340, 343 (2004). ¶ 14 Illinois law is clear regarding the effect voluntary unemployment can have on a child support obligation: "A party seeking to decrease his or her child support obligation based on a voluntary change in employment must demonstrate that the action was taken in good faith and not to evade financial responsibility to his or her children. Absent good faith, the voluntary termination of employment does not warrant an abatement of child support."

Decisions regarding what is required to prove a substantial change in circumstances for child support modification are plentiful. See In re Marriage of Adams , 348 Ill. App. 3d 340, 343, 284 Ill.Dec. 124, 809 N.E.2d 246 (2004) ("To establish a substantial change in circumstances, the petitioner must show an increase in the noncustodial parent's ability to pay and an increase in the needs of the child since the court's previous order."); see also In re Marriage of Turrell , 335 Ill. App. 3d 297, 307, 269 Ill.Dec. 633, 781 N.E.2d 430 (2002) ("The petitioning party must show both an increase in the child's needs and the supporting spouse's ability to pay."); In re Marriage of Rushing , 2018 IL App (5th) 170146, ¶ 34, 431 Ill.Dec. 236, 127 N.E.3d 769 ("To establish the change necessary to warrant an increase in support, a petitioner must show that the child's needs and the noncustodial spouse's ability to pay have increased."). Typically, a substantial change in circumstances means the child's needs, the nonmajority parent's ability to pay, or both have changed since the entry of the most recent support order.