If a custody order by the court, contains a detailed shared parenting plan which provides that the child will reside no less than one hundred eighty nights per calendar year in each parent's home, and that the parents will share the duties and responsibilities of parenting the child and the expenses of the child in proportion to their incomes, the court may, if deemed appropriate under the circumstances, grant a cross credit on the amount of the child support obligation based on the number of nights the child resides with each parent. The shared parenting child support cross credit shall be calculated as follows:
(1) Multiply the parents' combined child support obligation under the schedule by 1.5 to establish the parents' combined shared parenting child support obligation;
(2) Multiply the combined shared parenting child support obligation by each parent's percentage share of the parents' combined net incomes to establish each parent's shared parenting child support obligation;
(3) Multiply each parent's shared parenting child support obligation by the percentage of nights the child resides with each parent based on a three hundred sixty-five day calendar year to establish each parent's prorated shared parenting child support obligation;
(4) Offset the parents' prorated shared parenting child support obligations; and
(5) The parent with the larger prorated shared parenting child support obligation shall pay the difference between these amounts.
In deciding whether a shared parenting child support cross credit is appropriate, the court shall consider whether it would have a substantial negative effect on the child's standard of living.
It is presumed that the parenting time is exercised. If the parenting time exercised substantially deviates from the parenting time ordered, either party may petition the court for a modification of the support order without showing any other change in circumstances.