Money one parent pays the other toward a child's living costs, set in most cases by a state formula rather than by negotiation.
Child support is a payment toward the cost of raising a child, and the thing that surprises people most about it is how little discretion is usually involved. Federal law requires every state to publish numeric guidelines and to apply them as a rebuttable presumption, so in the ordinary case the amount is produced by running the parents' figures through the state's formula rather than by arguing about what is fair.
What the formula consumes differs by state - typically both parents' incomes, the number of children, the division of parenting time, and who pays for health insurance and childcare. A court can depart from the guideline figure, but it generally has to say in writing why the guideline result would be unjust or inappropriate in that case.
Two points cause most of the confusion. Support belongs to the child, not to the receiving parent, so parents cannot bargain it away between themselves in the way they can divide their own property. And support and parenting time are legally separate: withholding one because the other is not happening is not a remedy, and courts treat it as its own problem.
The two moments worth advice are when the order is first made - because the inputs to the formula, particularly income and parenting time, are where the real argument is - and when circumstances change. A support order does not adjust itself when someone loses a job or a child's needs change; it is modified by going back to court, and until that happens the existing order keeps running.
These directory pages each list at least one currently published law firm. The list is generated when this page loads, so a page whose listings have lapsed drops out rather than becoming a dead link.