Either parent may file a petition or motion to modify a child support order—upward or downward—but usually only when there is a substantial change in the child’s needs, or in one or both of the parents’ incomes or net resources, that justifies the court revisiting and possibly modifying the earlier child support order.

The petition or motion to modify child support generally must be filed in the same court that issued the original or most recent child support order. But if the child lives in a different county or state, the courts of the county or state where the child lives may be the proper place to file a petition or motion to modify a child support order.

In Massachusetts, either parent has the right to request a modification of a child support order. This can be done by filing a petition or motion with the court. However, the court will only consider such a request if there has been a substantial change in circumstances. This could include significant changes in the child's needs or a notable shift in the financial situation of either parent, such as a change in income or available resources. The standard for what constitutes a 'substantial change' can vary, but it generally must be significant enough to warrant a reevaluation of the child support amount. The modification petition or motion is typically filed in the same court that issued the original or most recent child support order. If the child has since moved to a different county or state, the petition or motion may need to be filed in the jurisdiction where the child currently resides. The process for modifying child support can be complex, and it may be beneficial for a parent to consult with an attorney to navigate the legal requirements and to ensure that their rights and interests, as well as the best interests of the child, are adequately represented.