simple three-step reduction of child support with increasing time-share. Application of this guideline can
result in several problems.
The first problem is that when there are only a few steps in the gradient, a cliff effect occurs after
each step. The Iowa guideline provides a three-step gradient, and the first step in that gradient is when the
lesser-time parent has the child 35 percent of the time. In a case in which both parents have equal annual
incomes of $30,000, a parent who has his or her child for 34 percent of the overnights per year would
have a monthly child support order of about $428, based on the Iowa basic sole custody guideline.
However, a parent with the same income, but who has his or her child for 3–4 additional overnights per
year over at the 35 percent-time threshold, would have a monthly child support order of only $363, a
reduction of $65 per month resulting from a 3–4 day increase in time-share.
A larger cliff effect occurs, however, between 49 and 50 percent time under the Iowa simple
graduated guideline. Using this same example of parents with equal annual incomes of $30,000, the
lesser-time parent would owe $321 per month at 46–49 percent time, but would owe nothing at 50
percent time.12 Figure 2 illustrates this (see also Appendix B1 for child support amounts in tabular form).
At higher incomes these cliff effects can become much larger.
Graduated guidelines suffer from a second serious concern in that they do not consider dissimilar
parental incomes. The thinking behind the graduated guidelines may be that the lesser-time parent is
usually also the greater-income parent (probably assuming that fathers are both the lesser-time parent and
the higher-earning parent). This can be an incorrect assumption; the lesser-time parent is often, in fact, the
12Iowa employs an “offset” formula for cases with 50/50 time-share, which results in an order of $0 in cases where the parents have equal incomes.
13Data from Cohorts 17, 18 and 21 of the Wisconsin Court Record Database indicate that in a sample of 228 unequal shared placement cases entering the Wisconsin court system from 1996 through 2002, 33 percent involved a situation where the lesser-time parent earned a lower income than the greater-time parent.