level and therefore a smaller cliff effect than Florida, which has a high threshold level of 40 percent. (The
numbers behind these figures are given in tabular form in Appendix B2.) Whatever the threshold,
however, all states using below-threshold offset formulas, complex or simple, have cliff effects.
Although a low threshold level reduces the size of cliff effects, it also allows situations where the
lesser-time parent, at fairly low time-share levels, can be named as the child support payee. At high time-
share levels it is desirable that a lesser-time parent could receive child support if the greater-time parent
has a higher income. However, at low levels of time-share, this might no longer be considered a positive
feature of offset formulas. For example, in the case of Louisiana, with a 20 percent threshold, it is
possible that a parent with only 21 percent time with the child could become the child support payee, if
the primary parent has a much higher income. This is shown on Appendix B6.
Above-Threshold Offset Formulas. Four states currently employ above-threshold offset formulas:
Hawaii, Montana, Utah, and Tennessee.18 The above-threshold offset formula differs from the other offset
formulas in that the threshold level is embedded in the formula. The formula, therefore, accounts only for
the percentage of above-threshold time that each parent has the child. (In contrast, all below-threshold
offset formulas consider the percentage of time for the entire year that the child is with each parent.)
Therefore, in a state like Montana, which has a 30 percent threshold, each shared custody parent has the
child for at least 30 percent time, leaving the remaining 40 percent of the year as above-threshold time.
The result of the Montana formula is that each parent is considered directly responsible for costs of the
child for 30 percent of the time, and the guideline then focuses on an appropriate child support order,
given the division of time-share for the remaining 40 percent of the child’s time.
The above-threshold offset formula can be expressed as a percentage or as a number of days. The
Montana formula with a 30 percent threshold looks like this, expressed in percentage terms:
18Tennessee has also implemented a second feature to its guideline that serves to penalize or to add a surcharge to parents who will be spending little or no time with their children: at time-share levels below 19 percent (69 days), an amount equal to 1/365th for each day less than 69 is added to the basic child support order.