For most separated families, child support is straightforward: the Federal Child Support Guidelines set a table amount based on the paying parent’s income, and that is the end of it. Shared parenting changes the analysis. Under section 9 of the Guidelines, once each parent exercises at least 40% of parenting time over the course of a year, the court is no longer bound to the table and may set a different figure.

Counting to 40%

The Guidelines do not prescribe a counting method, and it matters more than people expect. Courts most often count overnights, but in close cases they will count hours. Time at school or daycare is generally credited to the parent responsible for the child during that block, usually the parent who delivers and would respond in an emergency. An evening of dinner and homework does not convert into a full day, and padding the calendar is a credibility risk. If you are near the line, keep a precise, contemporaneous schedule for a representative period, because the threshold is a gate: below it, the table applies with full force.

Crossing the threshold: what section 9 actually requires

Meeting 40% does not automatically reduce support. The Supreme Court’s decision in Contino v. Leonelli-Contino establishes that all three statutory factors must be weighed:

• (a) The set-off. Calculate each parent’s table amount as if the other had the children full time, and subtract. If Parent A’s figure is $1,000 and Parent B’s is $600, the starting point is $400 payable by A. This is a starting point only, not a formula.
• (b) The increased costs of shared parenting. Two real households mean duplicated bedrooms, clothing, equipment, and activities. Courts examine the actual added spending, not an assumption that shared time is cheaper for the recipient or more expensive for the payor.
• (c) The conditions, means, needs and circumstances of each parent and child. This is where household incomes, standards of living, and the children’s actual needs enter. A judge can adjust the set-off up or down, or in the right case order the full table amount despite shared time.

The evidentiary burden is real. Courts expect sworn financial statements, budgets showing child-related spending in each home, and a clear picture of both households. Parents who arrive with the set-off math and nothing else routinely find the court defaulting toward the table amount, because the record gives it nothing to adjust with.

The anchoring principle

One idea runs through the caselaw: children should not experience a dramatic difference in standard of living between their two homes merely because the schedule changed. Support in shared parenting is not a discount program for payors or a windfall for recipients. It is a redistribution exercise aimed at the children’s actual lives in two households.

If you are approaching the 40% line, negotiating a shared schedule, or facing a claim to reduce support because of one, the quality of your financial evidence will usually decide the outcome. We help parents build that record properly, and we argue section 9 cases on both sides of it.