What it is: a legal change to an existing court order — for example, modification of parenting time (visitation), child support, or other terms originally ordered by the court.
What this means for you: life changes: a job loss, a promotion, a move. Illinois courts can change orders about support and parenting — but generally not unless circumstances have changed since the original order. You cannot simply stop paying and hope for the best; a motion for modification must be filed in court.
The key word is “substantial change.” A court won’t modify just because you’re unhappy; there has to be a material, ongoing change (not a temporary dip or a minor grumble). Document what changed — income, schedule, the child’s needs — before you file.
Watch out for: paying less (or more) “by agreement” with the other parent outside court feels easier, but it’s not enforceable and doesn’t change the order. If you want it to stick, put it before a judge.