- Child support is calculated primarily using the Federal Child Support Guidelines table amount, based on the paying parent's gross annual income and the number of children.
- The table amount covers ordinary expenses — Section 7 "special expenses" like childcare, medical costs, and extracurriculars are shared separately, usually proportionate to income.
- Shared custody (40%+ parenting time with each parent) can change the calculation using a different formula (the "set-off" method).
- Child support is the child's right, not something parents can simply agree to waive — courts can reject agreements that provide inadequate support.
- If a parent is underemployed or hiding income, courts can "impute" income based on earning capacity rather than accepting stated income at face value.
- Child support obligations generally continue until a child turns 18, and often longer if the child is in full-time post-secondary education.
The Guidelines Are Not Optional
Unlike many aspects of family law that involve negotiation and judicial discretion, child support in Ontario follows a legislated formula: the Federal Child Support Guidelines (for divorcing spouses under the Divorce Act) or Ontario's own parallel Child Support Guidelines (for unmarried parents under the Family Law Act). Both use essentially the same table amounts and principles.
This is a deliberate policy choice. Child support belongs to the child, not the parents, and the Guidelines exist specifically to remove it from the negotiating table as much as possible — reducing conflict and ensuring children receive consistent, predictable support regardless of how amicable or hostile their parents' relationship is.
Because the table amount is largely mechanical, disputes over child support in Ontario usually center on income determination — what a parent's true income actually is — rather than on what the appropriate support level should be once income is established.
The Table Amount: The Foundation of Every Calculation
The table amount is based on two inputs: the paying parent's gross annual income and the number of children being supported. Ontario has its own table (used for Divorce Act and Family Law Act cases where the payor resides in Ontario), with fixed amounts that increase with income and the number of children.
How the Table Works in Practice
The table amount is designed to reflect the average amount households at a given income level spend raising children. It is not calculated based on the specific child's actual expenses — it is a standardized amount intended to apply consistently across similar income levels.
A parent earning $70,000 per year with two children would owe a specific table amount set out in the Ontario table — the same amount that any other Ontario parent earning $70,000 with two children would owe, regardless of the specific family's actual spending habits.
Our free Child & Spousal Support Calculator can give you a preliminary estimate of the table amount based on income and number of children — a useful starting point before a full legal assessment.
Section 7 Special Expenses: Beyond the Table Amount
The table amount is meant to cover ordinary, day-to-day expenses of raising a child — food, clothing, housing. Certain additional expenses, called Section 7 special expenses, are shared separately between parents, typically in proportion to their respective incomes.
- Childcare expenses incurred so a parent can work, attend school, or due to a disability or illness.
- Medical and dental expenses exceeding insurance coverage by a certain amount.
- Health-related expenses such as orthodontics, counselling, or occupational therapy.
- Extraordinary extracurricular expenses for activities that go beyond what is reasonably included in the table amount, considering the family's means and the child's talents.
- Post-secondary education expenses, including tuition and related costs.
- Private school tuition, if this reflects the family's practice before separation or meets the child's particular needs.
Courts assess whether a claimed expense is genuinely "extraordinary" relative to the family's income and pre-separation lifestyle. A single expensive activity claimed without context can be disputed — proper documentation and a clear rationale strengthen a Section 7 claim significantly.
Shared Custody: How the Calculation Changes
When each parent has the child in their care at least 40% of the time (roughly 146 nights per year), the standard table amount calculation does not automatically apply. Courts generally use a modified approach known as the "set-off" method.
The Set-Off Method
Under this approach, the court calculates the table amount each parent would owe the other based on their respective incomes and the number of children, then the parent with the higher notional obligation pays the difference to the other parent. Courts also consider each household's actual increased costs from having the child a significant portion of the time, and any disparity between the parents' standards of living.
Even in shared parenting situations, courts have discretion to depart from a pure set-off calculation if it would not adequately meet the child's needs or would create an unfair disparity between households. The set-off amount is a starting point, not an automatic outcome.
Determining Income: Where Most Disputes Actually Happen
For salaried employees, income is usually straightforward — line 150 of the previous year's tax return, adjusted for any specific Guidelines rules. For others, determining "true" income can be far more contentious.
- Self-employed parents: Business income is scrutinized for personal expenses run through the business, and courts may add back certain deductions to reflect true available income.
- Parents with fluctuating income: Courts may average income over several years to smooth out irregular earnings, such as commission-based income or seasonal work.
- Parents with corporate income: Retained earnings in a corporation controlled by the parent may be attributed to them personally if used to artificially suppress reported income.
Imputed Income: When a Parent Isn't Earning What They Should
Courts will not allow a parent to avoid support obligations by remaining voluntarily unemployed, deliberately underemployed, or by hiding income. In these circumstances, a court can impute income — calculating support based on what the parent is capable of earning rather than what they claim to earn.
A parent with a professional degree and a decade of work history voluntarily takes a minimum-wage job shortly after separation. A court may impute income based on their demonstrated earning capacity and employment history, calculating child support as if they were earning at their prior professional level.
How Long Does Child Support Continue?
Child support generally continues until a child turns 18 and is no longer considered a "child of the marriage." However, support frequently continues beyond 18 in specific circumstances:
- The child is enrolled in full-time post-secondary education and remains reasonably dependent on their parents.
- The child has a disability or illness preventing them from becoming self-sufficient.
- The child otherwise remains under a parent's charge and cannot withdraw from their care.
Support for adult children in post-secondary education is often adjusted to reflect the child's own financial contributions, such as summer earnings, scholarships, or student loans, and may also be calculated differently than the standard table amount.
Changing an Existing Support Order
Child support orders are not permanent and unchangeable. Either parent can apply to vary support if there has been a material change in circumstances since the order was made — most commonly a significant change in either parent's income, a change in parenting time crossing the shared custody threshold, or a change in the child's needs.
| Change | Effect on Support |
|---|---|
| Payor's income increases | Support typically increases proportionately |
| Payor's income decreases (involuntarily) | Support may decrease if the reduction is genuine and not voluntary |
| Parenting time shifts to 40%+ shared | Set-off method may replace standard table calculation |
| Child turns 18, not in school | Support obligation may end |
| Child enrolls in post-secondary full-time | Support often continues, potentially recalculated |
Whether you are establishing, negotiating, or changing a child support arrangement, our Toronto family lawyers can help. Call 416-274-2222 for a free 30-minute consultation.
Frequently Asked Questions
Parents can agree to different arrangements, but courts will scrutinize any agreement providing less support than the Guidelines require, since child support belongs to the child, not the parents. A court can reject an inadequate agreement.
Yes. Child support should be recalculated when either parent's income changes materially. Many orders require annual income disclosure specifically so support can be adjusted to reflect current income.
Common Section 7 expenses include childcare costs, medical and dental expenses not covered by insurance, extraordinary extracurricular activities, private school tuition (in some cases), and post-secondary education costs.
Self-employed income is scrutinized closely, since business expenses can be used to artificially reduce reported income. Courts often add back certain discretionary business expenses when calculating income for support purposes.
When each parent has the child at least 40% of the time, courts can apply the "set-off" method — calculating what each parent would owe the other under the table amount, then having the higher earner pay the difference — plus considering each household's costs.
Yes, if the child remains a "child of the marriage" — commonly because they are enrolled in full-time post-secondary education and reasonably dependent on their parents, support can continue well beyond 18.
No. If a parent is voluntarily unemployed or underemployed without valid reason, courts can impute income based on their capacity to earn, calculating support as if they were earning what they reasonably could.
No. Unlike spousal support in some circumstances, child support payments are neither tax-deductible for the payor nor taxable income for the recipient under current Canadian tax law.