Enter your details to see results
Disclaimer: Table amounts are approximated from income; official federal tables vary by province and income bracket, and courts adjust set-offs under Contino. Estimate only — not legal advice.
Ordinary child support flows one way: the parent with less than 40% of parenting time pays the full table amount. Once each parent exercises at least 40% of parenting time over the year, s.9 of the Federal Child Support Guidelines changes the framework. The starting point becomes the set-off: compute each parent's table amount for all the children as though the other parent had them full-time, subtract the smaller from the larger, and the higher-income parent pays the difference.
In Contino v. Leonelli-Contino, 2005 SCC 63, the Supreme Court of Canada held that s.9 requires a contextual analysis, not arithmetic alone. After the set-off (s.9(a)), courts must consider the increased costs of shared custody (s.9(b)) — two homes each need bedrooms, clothing, and gear — and the condition, means, needs and other circumstances of each household (s.9(c)), including standard-of-living gaps between the homes. In practice, many orders land on the straight set-off, but a parent whose household would be visibly poorer can obtain more, and duplicated fixed costs can push the number above the pure difference.
Two children, with parenting time split 55/45. Parent A earns $95,000; the two-child table amount is about $1,410/month. Parent B earns $50,000; their table amount is about $755/month. The set-off is $1,410 − $755 = $655/month payable by Parent A. If Parent B's time were 38% instead of 45%, s.9 would not apply at all and Parent B would receive the full $1,410 — which is why a handful of overnights near the 40% line can be worth over $700/month and is litigated accordingly.
Get advice when parenting time hovers near the 40% threshold, when the other side proposes a schedule that looks support-driven, when household living standards diverge sharply, or when incomes need imputation before the set-off is run. Section 9 outcomes are more discretionary than any other Guidelines calculation — precise time records and full financial disclosure decide these cases.
Explore more free tools on our Family Law Calculators hub, walk through our interactive Family Law Wizards to understand your situation step by step, or contact LexScale.ai to build calculators like this for your own law firm website.
Enter each parent's gross annual income, the number of children, and each parent's percentage of parenting time. The tool estimates each parent's full child support obligation using a simplified table approximation, then applies the set-off: the higher obligation minus the lower one, payable by the higher-income parent. If neither parent reaches the shared custody threshold, the tool tells you the ordinary sole-custody table amount applies instead. Because official tables and state worksheets are more granular than any approximation, treat the output as a negotiation starting point, not the final number.
The threshold creates a well-documented cliff effect: a few overnights per year can swing support by hundreds of dollars a month. Judges know this and scrutinize whether a proposed schedule is driven by the child's interests or by support arithmetic. A parenting plan that plainly serves the child — school proximity, work schedules, sibling arrangements — will survive that scrutiny; a plan reverse-engineered from the support tables usually will not.
Child Support Calculator · Parenting Time Percentage · Section 7 Expenses Calculator · Imputed Income Calculator · Custody Time Calculator
Need legal help with your claim?
Ready to grow your firm with AI?