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 Indiana, either parent has the right to request a modification of a child support order if there has been a substantial and continuing change in circumstances that makes the current order unreasonable. This could include significant changes in a parent's income, the needs of the child, or other factors that affect the child support calculation. According to Indiana Code IC 31-16-8-1, a child support order can be modified upon showing a change in circumstances so substantial and continuing as to make the terms unreasonable, or upon showing that a party has been ordered to pay an amount that differs by more than 20% from the amount that would be ordered by applying the child support guidelines, and the order has been in effect for at least twelve months. The motion to modify child support should generally be filed in the court that issued the original order. However, if the child has moved to a different county or state, jurisdiction may lie in the new location where the child resides. It's important to consult with an attorney to understand the specific procedures and requirements for filing a petition or motion to modify child support in Indiana.