Yes. Under Utah Code Section 78B-12-203(5) (a) When possible, gross income should first be computed on an annual basis and then recalculated to determine the average gross monthly income. This includes commissions and any nonearned sources, such as investment income. You should average the recent sales together with the last 11 months of no sales. Once child support is set, the burden is on the party who wants to change it to file an action for change.