Child Support in Ontario: How the Guidelines Work

Child support is one of the most important issues to resolve when parents separate. It is also one of the more structured areas of family law — there are detailed guidelines that take much of the guesswork out of the calculation. Still, the details matter enormously, and knowing how the system works helps both parents understand what is fair and what to expect.

This article explains how child support in Ontario is calculated under the Federal Child Support Guidelines, how special expenses are handled, and what happens when parenting time is shared more equally.

The Legal Foundation: It's the Child's Right

Before getting into the numbers, it helps to understand the principle behind child support. Support belongs to the child — not to the parent receiving it. This means that parents generally cannot agree to waive child support entirely, and a court will not approve a separation agreement that purports to do so unless the arrangement genuinely meets the child's needs. A parent's right to receive support on behalf of a child cannot be bargained away for the parent's own benefit.

The Federal Child Support Guidelines

Child support in Ontario is governed primarily by the Federal Child Support Guidelines (which apply to divorces) and the parallel Ontario Child Support Guidelines (which apply to unmarried parents or married parents not yet divorcing). In practice, they follow the same structure and the same tables, so the calculation is the same regardless of which set applies.

The Guidelines use a straightforward approach: the amount of base support a paying parent owes is determined almost entirely by:

1. The payor's gross annual income
2. The number of children
3. The province where the payor lives

These inputs produce a table amount — a specific dollar figure (as of the last revision of the tables; verify current figures at Canada.ca or through a lawyer). The table amount is presumptively what a payor owes. It is not a starting point for negotiation — it is the amount, absent specific exceptions.

How Income Is Determined

The payor parent's income is calculated from their Line 15000 (total income) on their most recent income tax return, adjusted for certain items — for example, business expenses that reduce taxable income but do not reflect actual reduced earnings, or employment income that is understated due to use of a corporation.

If a parent is unemployed, underemployed, or self-employed in ways that obscure their actual earnings, a court can impute income — assign an income level that reflects the parent's earning capacity rather than what they actually reported. Courts take a dim view of parents who voluntarily reduce their income to avoid support obligations.

Income must be disclosed annually. Both parents have an ongoing obligation to provide updated income information, and failure to do so can result in court orders and cost awards.

Section 7: Special and Extraordinary Expenses

In addition to the table amount, parents may be required to share certain section 7 expenses — named after the section of the Guidelines that governs them. These are costs over and above day-to-day living expenses that are necessary for the child. Examples include:

• Childcare expenses (daycare, after-school care) required to allow a parent to work or study
• Medical and dental expenses not covered by insurance (above a reasonable threshold)
• Extracurricular activities, where they are extraordinary given the family's income and the child's needs
• Post-secondary education expenses
• Orthodontics and other extraordinary health costs

Section 7 expenses are shared proportionately to each parent's income, not split equally. If one parent earns twice as much as the other, they pay roughly two-thirds of the section 7 costs. Both parents should retain receipts, and it is common for separation agreements to set out how section 7 claims are submitted and paid.

What counts as a "reasonable" extracurricular expense has generated considerable litigation. Courts look at whether the expense was incurred during the relationship, whether both parents agree it is important for the child, and whether it is proportionate to the family's financial circumstances.

Shared Parenting and the "40 Percent Rule"

Where a child spends a substantial amount of time with both parents, the table-amount calculation can be adjusted. The Guidelines recognize a shared parenting arrangement where the child spends at least 40 percent of their time with each parent over the course of a year.

In shared parenting situations, the courts have discretion to reduce the table amount, replace it entirely with a different calculation, or in some cases set off each parent's table obligation against the other's. The reason is that when both parents have the child nearly half the time, both are incurring direct costs — and simply requiring one parent to pay the full table amount can over-compensate the other.

The 40 percent threshold is counted in time, not nights. Courts look at the overall pattern of the parenting schedule. An arrangement that is nominally "week on / week off" will generally meet the threshold, but not every case is straightforward.

Note that in Ontario, the terms decision-making responsibility (replacing "custody") and parenting time (replacing "access") are used in the Children's Law Reform Act. Child support is separate from parenting arrangements, and a parent cannot withhold support because they disagree with the other parent's decisions — nor can a parent withhold parenting time because support is unpaid.

When Does Child Support End?

Under the Federal Child Support Guidelines, child support continues for a child who is:

• A minor (under 18 in Ontario), or
• Over 18 but still dependent — typically because they are enrolled in full-time post-secondary education and have not yet become economically independent.

A child over 18 who has finished school and is self-supporting is generally no longer entitled to support. However, the transition is not always clean — a child may take time off school, return to school, or be in a hybrid situation. These scenarios often require updated legal advice.

Changing Child Support

Child support amounts must be updated when there is a material change in circumstances — typically a significant change in either parent's income. Because the Guidelines tie support to income, even modest income changes can affect the table amount.

Many separation agreements include a provision for annual exchange of income information and automatic recalculation when income changes significantly. This is good practice and avoids the need for a court application every time circumstances shift.

Frequently asked questions