There are many things that will be taken into consideration but in general either the parent who pays the support (the payer) or the parent who is the custodial parent (the payee) may ask the court for a hearing regarding a modification of the child support order.  In Iowa there must be a “substantial change of circumstances” for a child support order to be changed.  The two most common ways that this change can be shown is for the payee parent to show that the payer parent has health insurance that they did not have at the time of the order and that the insurance would cover the children or that the “10% rule” applies.  The “10% rule” says that if the amount the payer parent would have to pay would be 10% higher or lower than what they pay based on the previous order than this counts as a “substantial change of circumstances”.  It is important to note that a parent can not quit their job or decide to take a job that pays much less than their previous job and then turn around and say that they should not have to pay as much child support anymore.  The reduction of income must be involuntary in order to qualify for a new amount under the 10% rule.