other parent to less than 40 percent, then he/she would stand to gain financially. On the other hand, if the
lesser-time parent can increase his/her time to 40 percent or more, that parent will experience a
considerable financial gain. A struggle between the parents over the child’s time owing to a cliff effect in
a child support guideline, and perhaps having nothing to do with what is good for the child, can be
counterproductive to parental cooperation.
A Comparison of Formulas
The formulas used by the various states can be grouped into two broad categories, graduated and
offset formulas, distinguished by whether or not the greater-time parent’s income is used in the child
support reduction calculation. Graduated formulas do not consider the greater-time parent’s income when
calculating a reduction in child support.7
Under the graduated formula it is not possible to produce a child support order that would require
a high-earning greater-time parent to pay child support to a lower-earning lesser-time parent. Under offset
formulas, on the other hand, a high-earning greater-time parent may become the child support payor.
Both graduated formulas and offset formulas, along with a number of variations, are used by
different states. Different variations of the formulas have different characteristics and peculiarities at
various levels of time-share and with variations in parents’ relative incomes. A few states add to the
complexity of their guidelines by employing different formulas or variations at different levels of time-
share, most commonly making a distinction between unequal and equal time-share cases. We discuss a
number of the important variations of the basic formula types currently in use, but we generally do not
address the complexities introduced in a few states by the use of multiple guidelines at different points
along the time-share continuum.
7Graduated formulas may use the greater-time parent’s income to establish the level of basic child support that would be owed in a sole-custody case, however, these formulas do not consider the greater-time parent’s income in later steps of the calculation that would reduce the child support order in shared placement situations.