Family law
Can You Modify a Child Support Order That Was Entered by Default After a Custody Change?
Quick answer
An old child support order entered by default, without a real income calculation, does not have to stand forever. A new custody arrangement or a significant change in either parent's finances can open the door to a recalculation.
Last updated June 2026
Why a default order is not locked in
A default child support order is one entered when a parent missed a deadline or did not appear, so the court set support without full financial information from both sides. Courts generally treat these orders as fully enforceable until they are changed, so simply believing the number is wrong does not pause anything.
There are usually two different paths. One is asking the court to vacate the original default, which typically requires a reasonable excuse for the default and is much harder to win years later. The other, and usually more practical, path is filing for a modification, which asks the court to recalculate support going forward based on current facts. After several years have passed, most parents pursue modification rather than trying to undo the original order.
What usually counts as grounds to modify
Most states allow modification when there has been a substantial change in circumstances since the last order. A new court-ordered custody schedule that meaningfully changes how many overnights each parent has is one of the strongest examples, because parenting time is a core input in most support formulas.
Many states also allow modification after a set amount of time has passed since the order, or when a parent's income has changed by a significant percentage, without needing to prove anything else. In New York, for example, the Child Support Standards Act (CSSA) formula is supposed to drive the calculation, and an order that was never based on both parents' actual incomes is exactly the situation modification is designed to fix. Check your state's specific triggers, because the time periods and percentages vary.
How near-equal parenting time affects support
Equal or near-equal parenting time does not automatically mean support drops to zero. In some states, including New York, courts in true shared-custody situations often treat the higher-earning parent as the paying parent and then apply the formula, sometimes with adjustments. In other states, like California, the percentage of overnights is built directly into the guideline math.
This is why counting overnights accurately matters. Courts look at the actual schedule across the whole year, including summer and holiday time, not just the regular rotation. Bring a written count of annual overnights, the new custody order itself, and current income documents for both parents if you have them.
Why filing sooner is better
In nearly every state, a modification only reaches back to the date you filed the request, not to when your circumstances changed. Every month you wait is a month calculated under the old order, and courts almost never rewrite the past.
Practically, that means the strongest move after a custody change is to file the modification petition promptly, serve the other parent properly, and come to the hearing with complete financial disclosure. Since incomplete disclosure is often what caused a default order in the first place, being the parent with organized, complete paperwork this time around puts you in a much better position.
Tools and resources
This page is general legal information, not legal advice, and does not create an attorney–client relationship. Laws and local rules vary and change. For advice about your situation, consult a licensed family-law attorney in your state.