In Colorado, child support is determined using guidelines set forth by the state. The guidelines consider both parents' incomes, the number of overnights each parent has with the child, and various other factors like healthcare and daycare costs. If your ex's income decreases, it is possible that the child support payments could change, but it would require a significant change in circumstances. Furthermore, your ex would have to file for a modification with the court, and the court would need to determine that the modification was warranted. Generally the modification is retroactive to the date of filing.  Finally, you have defenses such that your spouse is unemployed or underemployed and can hire a vocational expert to testify if appropriate in your case.