Parents have the duty to support their children continuing until they reach 21 years old, is emancipated, or until death of the parent.

In New York, a child is emancipated when (s)he marries, joins the military, holds a full time job such that (s)he is self-supporting, or refuses to reasonable parental commands.  In other words, children who are of working age and are in their right minds when they choose to leave their homes without any real reason except to avoid parental control, give up their right to demand support, even if they are not financially self-sufficient. Bailey v. Bailey, 15 A.D.3d 577, 790 N.Y.S.2d 215 (2 Dept. 2005).  The non-custodial parent must make an application for the termination of child support upon the emancipation of the child.

In New York, child support is determined and awarded pursuant to the Child Support Standards Act (CSSA). Child support is usually paid by the non-custodial parent for the support, maintenance and education of the children (basic child support). It generally does not include voluntary gifts, clothes, transportation, vacation expenses or rent for the benefit of the child and thus these items may not be considered "child support". In addition, each parent is responsible for their pro-rata share of childcare, uninsured healthcare and educational expenses as add-ons.  (Scheinkman, Practice Commentaries, McKinney’s Cons Laws of NY, Book 14, Domestic Relations Law § 240, at 250.) Further, the custodial parent in New York State is not required to provide an accounting with regard to the child support payment.

For the purposes of the CSSA, “adjusted” gross income is defined as gross income less certain deductions that are permitted. These permitted deductions are as follows: (a) certain unreimbursed employee business expenses; (b) maintenance paid to a spouse not a party to the current action for child support, but only if there is a court order or properly written agreement; (c) maintenance paid to a spouse who is a party to the current action, but only if there is an existing order or a properly written agreement; (d) child support paid pursuant to a court order or properly written agreement to a child who is not part of the pending action; (e) public assistance; (f) Supplemental Security Income; (g) New York City or Yonkers income or earnings taxes actually paid; and (h) Federal Insurance Contributions Act (FICA) taxes.

Thereafter, the “adjusted” gross income amount is multiplied by the guideline percentage for the number of children (may also refer the CSSA chart) . The "child support percentage" is fixed as follows: a) 17% of the combined parental income for one child; b) 25% of the combined parental income for two children; c) 29% of the combined parental income for three children;  d) 31% of the combined parental income for four children; and e) no less than 35% of the combined parental income for five or more children.  The law provides that for combined income up to $130,000, the calculation of basic child support should strictly adhere to the guidelines (although the law does allow for deviations where the CSSA amount would be unfair and unreasonable).