Modifying child support
Three routes:
- A substantial change in circumstances since the order
- A change of 15% or more in either parent’s income
- Three years having passed since the order was entered or last modified
Under Family Court Act §451, substantial change is a ground for modification. The three-year and 15% gross-income grounds apply unless the parties specifically opted out in a valid agreement or stipulation; their applicability also depends on the order and agreement dates. An income reduction must be involuntary, with diligent efforts to obtain suitable employment.
The three-year and income-change grounds can permit review without proving a separate substantial change, subject to the applicable dates, opt-out terms and income-reduction conditions.
Modifying custody
Harder, and deliberately so. Courts value stability for children and are reluctant to relitigate custody on a parent’s dissatisfaction.
You must show a substantial change in circumstances, and then that modification serves the best interests of the child. Both, in that order. Common grounds include a relocation, a material change in a child’s needs, a change in a parent’s circumstances or availability, or a sustained pattern of one parent frustrating the order.
A parent’s preference is not a change in circumstances. Neither, on its own, is a new partner or a better house.
The mistake that costs the most
Support does not adjust itself. A parent who loses a job and stops paying does not have a defense — they have arrears. Those arrears generally cannot be cancelled retroactively even where the reduction would clearly have been granted had it been sought.
The rule is simple and the consequence of ignoring it is severe: file when the change happens, not when you can afford a lawyer. A petition filed promptly protects the position from the filing date. One filed a year later does not reach back.
The same principle applies to custody. Informally agreeing to a different schedule and operating that way for years creates a mess — the order says one thing, the family does another, and whoever wants to enforce the order can.
What if we agree?
Modifications by agreement are common and straightforward, but the agreement should be put into a court order. An informal arrangement between cooperative parents holds only while both remain cooperative, and it provides nothing to enforce if that changes.
Frequently asked questions
How do I change a child support order in New York?
By petition. A substantial change is one ground. Unless validly opted out, three years since entry, modification or adjustment, or a change of at least 15% in either party’s gross income, may provide another ground for eligible orders. Income reductions must be involuntary with diligent efforts to obtain suitable work.
Can I stop paying support if I lose my job?
No. The order remains enforceable until modified, and arrears accrue in the meantime. File for modification immediately rather than stopping payment.
How hard is it to change custody?
Harder than support. You must show a substantial change in circumstances and that modification is in the child’s best interests. Dissatisfaction with the existing arrangement is not enough.
Can we just agree to change it ourselves?
You can agree, but put it into a court order. An informal arrangement is unenforceable and the original order remains binding.
Does the court apply the change retroactively?
Generally back to the filing date, not to when the change occurred. This is why prompt filing matters.
Related: Enforcement / Violation Petitions · Child Support · Child Custody & Parenting Time · back to Family Law
Written by Dale Riedel, Esq. · Admitted in New York, Bar No. 5837539 · Last reviewed October 6, 2026