The general rule is that courts have the exclusive authority to modify child support and are not bound by the parties’ agreements concerning child support. Blisset v. Blisset, 123 Ill. 2d 161, 167 (1988). In Blisset, Illinois’ supreme court held an out of court agreement to waive child support in exchange for a waiver of visitation rights was not enforceable because the parties did not seek court approval of their agreement.
So, if you have an understanding with your ex that you want to deviate from the previously written and entered order you should, ideally, go to court to modify that order. The court will then issue you a new order that will control.
But, the reality is, that parties often come to agreements outside of the order. Whether it be a new pick and drop off schedule to an agreement as to who will pay what for braces, an agreement that is not in writing is obviously superior to no agreement at all. Those unwritten agreements, however, are often considered to be just temporary. Should the parties disagree again and one of the original parties opts to revert to they written agreement, the written agreement will control.
If you do have an out-of-court agreement, whether it’s written or just oral, you can try to make it as valid as a court entered order by relying on “equitable estoppel”
Equitable estoppel exists where a party, by his or her own statements or conduct, induces a second party to rely, to his or her detriment, on the statements or conduct of the first party. In re Marriage of Smith, 347 Ill. App. 3d 395, 399 (2004). The party who asserts estoppel must have relied upon the other party’s acts or representations and not have any knowledge or convenient means of knowing the facts, and such reliance must have been reasonable. Id. A finding that equitable estoppel applies must be based upon clear and convincing evidence and will not be reversed unless the trial court abused its discretion. In re Marriage of Duerr, 250 Ill. App. 3d 232, 237 (1993).
The basic concept is that a deal is a deal so long as you gave up something to get the deal. For example, if you agreed to pick up the child at daycare even during the other parent’s time in exchange for a reduction in the child support owed, that may be held to be sufficient equitable estoppel to be a controlling agreement. In this case, you gave something up to your detriment (your time to pick up the child) in exchange for a new deal (a reduction in child support)
The hard part is often proving that a deal existed when it wasn’t written. This is usually best done by proving the detriment. If you can prove that you gave something up to the other party, logically there must have been a reason that you did so. Then again, just because you can prove the detriment does not mean you can prove the agreed upon benefit. Especially, if it hasn’t occurred yet (such as the reduction in child support owed).
The obvious solution to these problems with out-of-court agreements is to get them in writing. Even a recorded back and forth via text message would be sufficient.
The only guaranteed modification to an order is one done within the courts. If your agreement is significant and especially if it involves money, I would recommend you file a motion to modify.