Generally, courts entertain motions to modify child custody and child and spousal support because of changed circumstance in the lives of the custodial or noncustodial parent in the case of custody and child support, or in the lives of the payer or payee in the case of alimony. Changed circumstances very often involve reduced or increased income of one of the parties. In the case of custody, once it has been determined, any subsequent changes in the parenting plan must be made with the approval of the court. When both parents agree on the changes, the court normally approves them. If the one parent disagrees with the desired changes, however, the other must persuade the court that the changes are in the best interests of the child or children, and request that the court order those changes be incorporated into the parenting plan.

To successfully request a court-ordered change in custody, the court must find that a substantial change in circumstances has taken place since the initial (or previous) custody determination was made. What constitutes a substantial change in circumstance can be perplexing. In some cases a parent presents numerous, valid concerns about the current custody arrangements, yet those concerns do not meet the definition of a substantial change in circumstances. If this parent goes to court to ask for a modification of the parenting plan, he or she will almost certainly be denied their request, since they have not met the criteria the court requires for a change to be made.

Custody and child support are parameters of a divorce with a very long trajectory. Normally visitation happens for the duration of custody, and child support lasts as long as both visitation and custody. Child support generally continues until:

In addition, an informal change of custody will not necessarily stop a parent’s support obligation - only a court order can provide certainty of that.

A noncustodial parent cannot withhold child support because his or her former partner refuses him or her visitation. Child support payments and visitation are considered by the law to be separate issues. When one spouse fails to live up the terms and conditions of visitation, the other spouse needs to go back to court to enforce the court order. Regardless of any visitation issues, parents have a legal responsibility and moral obligation to support their children. Other changes in visitation follow the same general court procedures as changes in custody.

In order to discourage parents from constantly litigating custody, some states apply a special standard for custody modifications sought within the first year or two after a prior custody order. In those states, the parent must show not only a change of circumstances, but also that the child is endangered by the child’s current environment. After expiration of the one- or two-year period, the courts apply normal standards for modification (without having to show endangerment).