How is Child Support Calculated?


In Canada, we have a convenient framework for completing child support calculations: The Federal Child Support Guidelines [“The Guidelines”]. The Guidelines are a set of rules and tables designed to determine the amount of financial support a parent should pay for the care of their children after a separation or divorce. The Guidelines apply to parents who are divorcing and, in most cases, to those who were never married but are separating and have children that reside in a province or territory where The Guidelines are applicable. They also generally apply to parents that have never lived together at all.

The objectives of The Guidelines are to:

    1. Establish a fair standard of support for children that ensures that they continue to benefit from the financial means of both spouses after separation.
    2. Reduce conflict and tension between spouses by making the calculation of child support orders more objective.
    3. Improve the efficiency of the legal process by giving courts and spouses guidance in setting the levels of child support orders and encouraging settlement.
    4. Ensure consistent treatment of spouses and children who are in similar circumstances.

In keeping with these objectives, child support obligations are not set in stone and may be adjusted based on individual circumstances. However, it is worth noting that the figure produced by The Guidelines is presumed to be correct in the absence of any reason that it is not appropriate.


In most circumstances, child support is calculated through the following steps:

    1. Determine the income of the payor.

The starting point is to use the payor’s income as reported on line 150 of their annual tax returns. However, it may not be this simple if a payor parent is unemployed, underemployed, or has other sources of unreported income. There are also types of deductions that are typically subtracted from a payor parent’s income for the purposes of child support—fees or dues payable to a union are one example. Further, The Guidelines may not be applicable if the annual income of the payor parent is greater than $150,000.00.

Note that if both parents have the children in their care for a period greater than 40% of the time, both parents become “payor parents” and are obligated to pay child support to each other. That’s a topic for another day.

2. Determine the number of children eligible for support.

A child’s eligibility for child support is not as cut and dry as one might think. There are circumstances where a payor may be responsible for paying child support for children that are not their biological children. There are also circumstances where children may be entitled to continue receiving child support even after reaching 18 years of age. This is common if they are pursuing
postsecondary education or are otherwise unable to obtain the necessaries of life without financial support.

3. Review the tables in The Federal Child Support Guidelines.

Once the income of the payor parent and the number of eligible children is determined, a payor can review the tables included at the back of The Guidelines to determine what their monthly child support obligation is. The applicable table will produce a monthly dollar figure payable to the other parent each month.

4. Consider exceptions and variations.

The Guideline amount will not be strictly applicable in certain situations. In circumstances where paying the Guideline amount would cause undue hardship to the payor parent, the Guideline amount may be deemed inappropriate. Just because a child support amount is appropriate at one time does not mean it will always be appropriate. There may be changes in the children’s or parents’ circumstances that justify a variation of the payor parent’s child support obligation.

5. Consider special or extraordinary expenses.

In addition to the table amounts, The Guidelines provide for the sharing of special or extraordinary expenses. These might include childcare expenses, educational expenses, healthcare needs (such as orthodontics), and extracurricular activities. Expenses that fall under this section are typically shared in proportion to the parents’ incomes. So if one parent earns $60,000.00 and the other parent earns $40,000.00, expenses for the children would be apportioned 60% to 40%.

Note that this apportionment applies only to the “out of pocket” value of these types of expenses after using any applicable benefits or insurance coverage and considering any applicable tax deductions that might lessen the expenses. All expenses that are considered “special or extraordinary expenses” are in addition to the child support figure provided by the tables in The Guidelines.

Also note that because the figures produced by the tables in The Guidelines are unrelated to the receiving parent’s income, the receiving parent may not be required to provide financial information in many circumstances. However, the receiving parent is required to provide financial information if there are special or extraordinary circumstances at play so that these expenses can be apportioned proportionately to income pursuant to section 7 of The Guidelines.


The Federal Child Support Guidelines provide a convenient framework for calculating child support obligations. This framework is based solely on the calculated income of the payor and the number of children eligible for support, and subject to the exceptions outlined in The Guidelines. There is also a separate calculation completed for special or extraordinary expenses as defined by section 7.

Given the complexity and potential for variation based on individual circumstances, it is prudent for parents to seek legal advice when working with child support matters. A lawyer can help navigate the specifics of The Guidelines, including any provincial or territorial differences, and ensure that
the amount of child support is fair, reasonable, and in the best interests of the child or children involved.

Section 1: Objectives
Section 3: Amount of Child Support
Section 7: Special or Extraordinary Expenses
Section 15: Determination of Annual Income
Section 16: Calculation of Annual Income

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