Under graduated guidelines, a low-earning mother who has the child for less than one-half time,
but for a substantial period of time, say 46 to 49 percent, would be ordered to pay child support to a very
high-earning father. A graduated guideline does not provide for child support to be paid to parents who
have the child a substantial, though less than half, amount of time, no matter how great the income
disparities. Appendix B2 shows this situation. A lesser-time parent in Iowa with a substantial level of
time-share, 46 to 49 percent time, earning $30,000 annually, would be ordered to pay $302 per month to a
greater-time parent who earned $40,000 annually, a potentially troubling order given the near equal levels
of time share and the different income levels of the two parents.
Returning to the issue of cliff effects, this lower-earning parent could receive $93, rather than pay
$302 per month, simply by increasing his or her time from 49 percent to 50 percent—a change in the net
income of the lower-income parent of $395 for an increase in time with the child of one percentage point.
Figure 3 illustrates this by showing the child support order amount falling below the $0 line, into negative
numbers at the 50 percent time-share level. The simple gradient guideline risks parental discord over
small increments in time-share.
The largest class of child support guidelines that address shared-time situations are “offset”
formulas, which function by off-setting the parents’ incomes – one against the other. Offset formulas
currently in place in various states differ widely, however, in several respects. These differences produce
different problems in the application of the formulas and different levels of child support orders across
states for similar income and time-share situations.
Offset formulas are generally used in combination with a particular threshold of time-share. The
main function of a state’s threshold is to indicate the minimum level of time that the lesser-time parent
must spend with the child for which the state will consider a reduction in child support.
Thresholds also function in another way, to limit child support orders that might otherwise be
given to high-income, greater-time parents. For example, in states with a 30 percent threshold, in no case