N.Y. Fam. Ct. Act § 451 : FAMILY COURT — SUPPORT PROCEEDINGS — COMPLIANCE WITH ORDERS — Continuing jurisdiction

1. Except as provided in article five-B of this act, the court has continuing jurisdiction over any support proceeding brought under this article until its judgment is completely satisfied and may modify, set aside or vacate any order issued in the course of the proceeding, provided, however, that the modification, set aside or vacatur shall not reduce or annul child support arrears accrued prior to the making of an application pursuant to this section. The court shall not reduce or annul any other arrears unless the defaulting party shows good cause for failure to make application for relief from the judgment or order directing payment prior to the accrual of the arrears, in which case the facts and circumstances constituting such good cause shall be set forth in a written memorandum of decision. A modification may increase support payments nunc pro tunc as of the date of the initial application for support based on newly discovered evidence. Any retroactive amount of support due shall be paid and be enforceable as provided in section four hundred forty of this article. Upon an application to set aside or vacate an order of support, no hearing shall be required unless such application shall be supported by affidavit and other evidentiary material sufficient to establish a prima facie case for the relief requested.
2. A proceeding to modify an order of support shall be commenced by the filing of a petition which shall allege facts sufficient to meet one or more of the grounds enumerated in subdivision three of this section.
3.
(a) The court may modify an order of child support, including an order incorporating without merging an agreement or stipulation of the parties, upon a showing of a substantial change in circumstances. Incarceration shall not be considered voluntary unemployment and shall not be a bar to finding a substantial change in circumstances provided such incarceration is not the result of non-payment of a child support order, or an offense against the custodial parent or child who is the subject of the order or judgment.
(b) In addition, unless the parties have specifically opted out of the following provisions in a validly executed agreement or stipulation entered into between the parties, the court may modify an order of child support where:
(i) three years have passed since the order was entered, last modified or adjusted; or
(ii) there has been a change in either party's gross income by fifteen percent or more since the order was entered, last modified, or adjusted.

A reduction in income shall not be considered as a ground for modification unless it was involuntary and the party has made diligent attempts to secure employment commensurate with his or her education, ability, and experience.

N.Y. Family Court Law § 451

Amended by New York Laws 2019, ch. 313,Sec. 3, eff. 9/13/2019.
Amended by New York Laws 2014, ch. 373,Sec. 1, eff. 12/22/2014.