Child Support in Shared Parenting Arrangements

What Makes an Arrangement "Shared" for Support Purposes?

Section 9 of the Federal Child Support Guidelines applies where a child spends a significant amount of time in each parent's care over the course of a year. This is commonly discussed as a threshold of around 40% or more of the time with each parent, but the guideline's underlying concept looks at care and control of the child, not simply the number of overnights on a calendar. Courts retain discretion in how they apply this idea to a particular family's schedule, so the exact threshold and how time is counted can itself be a point of disagreement between parents. Confirm the current guideline text and get advice on your own numbers rather than relying on a rule of thumb.

This page focuses specifically on how support is calculated once an arrangement is treated as shared for these purposes. For the parenting-time side of shared parenting — schedules, decision-making, and how the two concepts relate — see Shared Parenting in Ontario.

It also matters what "time" is being measured. The relevant idea is generally understood as time the child is in a parent's care and under that parent's responsibility, not necessarily only the hours a parent is physically in the same room as the child — for example, time a child spends at school or in child care during a parent's scheduled time is commonly still counted as that parent's time. Because this can be counted in more than one way, parents sometimes disagree about whether their own arrangement actually meets the general threshold, even when the parenting schedule itself is not in dispute.

The Three Factors Courts Consider

Where section 9 applies, the Guidelines direct a court to determine the amount of child support by taking into account three things together, not any single one of them alone:

• The table amounts. The amount each parent would otherwise pay under the applicable Child Support Guidelines table, based on their own income and the number of children.
• The increased costs of the shared arrangement. The extra expense generally involved in a child effectively needing two functional homes rather than one.
• The condition, means, needs, and circumstances of each parent and child. A broader look at each household's overall financial position and the child's needs.

Canadian courts, including the Supreme Court of Canada, have confirmed that all three factors are meant to be weighed together, with no single factor treated as automatically decisive. Because of this, two families with similar incomes and similar parenting schedules can still end up with different support outcomes once a court looks at their full circumstances.

Section 9 does not set out a formula for combining the three factors into a single number, and it does not say how much weight any one factor should be given relative to the others. Instead, it leaves that balancing to the court (or, where parents agree between themselves in a separation agreement, to negotiation informed by all three factors). This is different from the regular table calculation, which is a comparatively mechanical lookup based on income. Because a shared-parenting analysis involves more judgment, parents and their advisors often spend more time gathering evidence and preparing argument on this issue than on a straightforward, non-shared child support calculation.

Why It's Not Just "Netting" the Two Table Amounts

A common shorthand is to describe shared parenting support as a "set-off": look up each parent's table amount, subtract the smaller figure from the larger, and the difference becomes the support payment. This set-off is often used as a starting reference point — the shared parenting calculator can help illustrate one — and in some straightforward cases it may end up close to the final result. But it is generally understood as only the first step of the analysis, not the answer on its own.

Courts have held that relying on a straight set-off alone can understate what a child actually needs, particularly where the parents' incomes differ significantly or one household bears disproportionately more of the day-to-day costs of raising the child. That is why the Guidelines direct a court to also weigh increased costs and each parent's and child's broader circumstances before settling on a final figure. Outcomes vary considerably from case to case, and there is no fixed formula that reliably predicts the result.

This matters in practice because a set-off calculation, on its own, treats support as purely a function of the two incomes and the number of children, without asking whether that number actually reflects what the child needs in a shared arrangement, or whether it leaves one household unable to provide reasonably comparable care. A lower-income parent with the child a large share of the time, for instance, may still face meaningfully higher day-to-day costs than the set-off figure alone would suggest, which is part of why the broader circumstances factor exists alongside it.

Increased Costs of Shared Parenting

Maintaining a child across two homes generally costs more, in total, than raising the same child primarily out of one home with visits to the other. Bedrooms, furniture, everyday supplies, and sometimes clothing and equipment may effectively need to exist in duplicate. A court considering this factor generally looks at evidence about what the arrangement actually costs in practice, rather than applying a fixed dollar figure or percentage increase. Parents who believe increased costs are relevant to their situation are generally expected to be able to explain and, where possible, support those costs with some evidence.

It is not automatically assumed that increased costs exist, or that they are significant, in every shared arrangement — some families already have most of what a child needs in both homes before separation, which can reduce how much this factor changes the outcome. Where increased costs are raised as an issue, being able to point to specific, concrete expenses generally carries more weight than a general assertion that shared parenting "costs more."

Each Parent's Means and Circumstances

The third factor lets a court look beyond a straight comparison of the two parents' incomes. It can take into account each parent's overall financial position, debts, and obligations, along with the child's own needs, and adjust the outcome where a plain set-off would leave the child experiencing a standard of living that differs sharply between the two homes. This factor is highly fact-specific, and how much weight a court gives it depends heavily on the evidence in each case.

How This Differs From the Regular Table Calculation

In a typical arrangement where a child lives primarily with one parent, child support is usually calculated by looking up a single table amount based on the paying parent's income and the number of children, without the additional layers described above. Section 9 replaces that straightforward lookup with a three-factor analysis once parenting time is shared. For the general table calculation, special expenses, and the broader rules that apply outside a shared-parenting situation, see Child Support Calculations and Child Support in Ontario. Costs beyond the basic table amount, such as childcare or health-related expenses, are generally addressed separately as special or extraordinary expenses, whether or not an arrangement is shared.

Shared Parenting Time vs. Shared Decision-Making

Section 9 is concerned only with parenting time — how a child's time is actually divided between two homes. It has nothing to do with decision-making responsibility, which covers who has authority over choices like health care, education, and religion. Parents can share decision-making without sharing time close to equally, and parents can share time close to equally while one of them holds most or all decision-making responsibility. Only the time-sharing side is relevant to whether section 9 applies to a support calculation. For a fuller explanation of both concepts and how they relate, see Shared Parenting in Ontario and Parenting Time.

Common Misunderstandings

• Assuming close to equal time automatically means no support is owed
• Treating the set-off amount as the guaranteed final figure
• Confusing shared parenting time with shared decision-making responsibility
• Overlooking that increased-costs and circumstances evidence can shift the outcome
• Assuming the percentage threshold is a precise, universally fixed number
• Expecting an agreement reached between parents to be automatically binding on a court later
• Assuming section 9 applies the same way regardless of how many children are involved, or their ages
• Waiting until a dispute arises to start keeping track of actual parenting time

Because so much of this analysis depends on the specific facts of a family's situation — actual parenting time, actual costs, and each parent's actual financial circumstances — general information like this page can explain the framework, but cannot tell you what outcome a court would reach on your own numbers. Keeping clear records of the parenting schedule that is actually followed, and of costs connected to the shared arrangement, generally makes this kind of analysis easier later, whether the amount is worked out by agreement or decided by a court.

Frequently Asked Questions