The noncustodial parent either loses his or her job or gets a promotion, has another child or receives a big inheritance. Or maybe the shared child starts starts attending a better school or begins participating in more expensive extracurricular activities. These are all examples of situations in which one or both parents may wish to see out modifications to a child support agreement.
Child support is intended to replicate the level of financial report would have been available to them to cover their expenses had his or her parents never separated. A lot of different factors shape how much the custodial parent is awarded to take care of their child, including how much income each party receives and how many other kids a parent has to support.