What percentage of parenting time triggers the shared-custody child support rule?

Under the Child Support Guidelines, the special shared-custody calculation applies when a child spends at least 40 percent of the time with each parent. This threshold is the dividing line between the standard table amount and the discretionary shared-custody calculation. Below 40 percent, the standard table applies and the payor pays the full table amount. At or above 40 percent, the court applies a more discretionary approach that considers both parents' costs and incomes.

The 40 percent is measured across the full year — not just a typical week. Courts look at the total number of overnights and time periods across 12 months, including holidays, summer, and extended parenting time. A schedule that is 40/60 when looking at school weeks might cross the 40 percent threshold when summer months are included, or vice versa.

It is worth noting that crossing the 40 percent threshold does not automatically reduce support to zero or even dramatically reduce it. The discretionary calculation can still result in a meaningful payment from the higher-earning parent to the lower-earning parent. The threshold is the trigger for applying a different method, not a guarantee of a different outcome. If your parenting schedule is near the 40 percent line, careful calculation of actual time is important before taking a position in negotiations.