How Is Child Support Calculated in Ontario?

In Ontario, basic child support is the amount in the federal child support table for the paying parent's province, based on that parent's annual income and the number of children. Special or extraordinary expenses, such as child care or braces, are then added and shared in proportion to both parents' incomes.

How child support is worked out in Ontario, step by step

Child support is the part of family law with the clearest formula. Most of the work is getting the income right and spotting the situations where the formula changes. This page walks through the calculation the way a court, a lawyer or the Ontario Child Support Service approaches it. For the wider picture of support after separation, including spousal support, see our child and spousal support page.

Two sets of rules apply in Ontario, and they are written to match. The Ontario Child Support Guidelines (O. Reg. 391/97) apply to claims under the Family Law Act, which covers unmarried parents and married parents who are not divorcing. The Federal Child Support Guidelines apply when child support is claimed in a divorce under the Divorce Act. Both use the same federal tables.

Identify the paying parent. Usually this is the parent who has the child less of the time. The Ontario guidelines define "majority of parenting time" as more than 60 per cent of parenting time over the course of a year.
Pick the right table. The table is the one for the province or territory where the paying parent ordinarily lives when the application is made. If the paying parent lives in Ontario, the Ontario table applies, even if the child lives elsewhere.
Find the paying parent's annual income. The starting point is the "Total income" figure on the parent's T1 General tax return, then adjusted under Schedule III of the guidelines (for example, deducting certain employment expenses, or replacing the taxable amount of dividends with the amount actually received).
Read the table amount. The table gives a monthly amount for the number of children and that income. For incomes over $150,000, the court can use the table or set a different amount on the income above $150,000.
Add section 7 expenses. Child care, the child's share of health and dental premiums, uninsured health costs over $100 a year, and some school, post-secondary and extracurricular costs can be added and shared by income.
Check for a special situation. Shared parenting (each parent has at least 40 per cent of the time), split parenting, a child 18 or older, or a claim of undue hardship can each change the result.

Since October 1, 2025, the updated federal tables apply to all Ontario child support matters. Ontario's Child Support Service confirms that notices of calculation and recalculation it issues on or after that date use the 2025 table amounts. The official Government of Canada 2025 child support table look-up gives the table figure for a given income, province and number of children.

What goes into the calculation

Piece	What it means	Rule in the Ontario guidelines
Table amount	The base monthly amount for the number of children and the paying parent's income	Section 3(1)(a)
Special or extraordinary expenses	Child care, health, education and some activity costs, shared in proportion to income	Section 7
Income over $150,000	Table amount on the first $150,000, a court-set amount on the rest, if the full table amount is inappropriate	Section 4
Split parenting time	Each parent has the majority of time with at least one child; the two table amounts are set off	Section 8
Shared parenting time	Each parent has the child at least 40 per cent of the time over a year	Section 9
Undue hardship	A different amount where the table would cause undue hardship and the claimant's household is not better off	Section 10
Income determination	T1 "Total income", adjusted by Schedule III; three-year pattern or imputed income where fair	Sections 15 to 19

How income is decided when the tax return does not tell the whole story

For an employee with a steady salary, income is usually simple: the most recent tax return and a current pay stub. It gets harder for people who are self-employed, own a corporation, earn commissions or bonuses, or recently changed jobs. The guidelines give the court three tools, and we explain each in our page on what counts as income and when income can be imputed.

Pattern of income. If the latest year is not the fairest measure, the court may look at the last three years and set a fair amount in light of a pattern, a fluctuation or a one-time payment (section 17).
Corporate income. Where a parent is a shareholder, director or officer, the court can include some or all of the corporation's pre-tax income if the parent's personal income does not fairly reflect the money available (section 18).
Imputed income. The court may impute income in listed situations, including where a parent is intentionally under-employed or unemployed, has failed to provide income information when required, or unreasonably deducts expenses (section 19).

Disclosure drives all of this. A parent who applies for child support must file three years of tax returns and notices of assessment, a current statement of earnings, and business or corporate records where they apply (section 21). A parent who is served must provide theirs within 30 days if they live in Canada or the United States, or 60 days if they live elsewhere.

What changes the answer

The table amount is the presumptive rule, but several situations move the number up or down.

Special expenses. Section 7 expenses are often the largest part of a dispute. Each one is tested for necessity in light of the child's best interests and reasonableness given the family's means and past spending. Our page on special or extraordinary expenses explains each category.
Shared parenting. When each parent has the child at least 40 per cent of the time over a year, section 9 requires the court to consider both table amounts, the increased costs of the shared arrangement, and each household's circumstances. See how child support works with shared parenting.
A child 18 or older. For a child at or over the age of majority, the court may apply the guidelines as usual or, if that is inappropriate, set an amount based on the child's means and needs (section 3(2)). Our page on whether child support ends at 18 covers post-secondary students and adult children with disabilities.
Undue hardship. A parent with, for example, unusually high debts reasonably incurred during the relationship, or a legal duty to support other children, can ask for a different amount. The request must be denied if that parent's household would have a higher standard of living than the other household. See reducing child support for undue hardship.
Agreements and consent orders. Parents can agree on a different amount, and a court may approve it on consent if reasonable arrangements have been made for the child (Family Law Act, s. 33(14)). The court still has regard to the guidelines.
Medical and dental coverage. Where coverage is available through work or otherwise at a reasonable rate, the court may order a parent to get it or keep it (section 6).

If both child and spousal support are claimed, the Family Law Act tells the court to give priority to child support (s. 38.1).

A worked example

For example, imagine two parents who separate in Toronto. Their seven-year-old lives with one parent most of the time and sees the other parent every second weekend and one evening a week. The parent with less time earns $90,000 a year as an employee, and the parent with the child most of the time earns $60,000. The child is in after-school care that costs $5,000 a year after subsidies, benefits and tax deductions or credits are taken into account, as section 7(3) requires.

The first step is the table amount: the monthly figure in the 2025 Ontario table for one child at an income of $90,000. Parents can look this up in the official federal look-up. The second step is the after-school care. Combined income is $150,000. The paying parent earns 60 per cent of that ($90,000 divided by $150,000) and the other parent 40 per cent. So the paying parent contributes $3,000 a year ($250 a month) toward child care on top of the table amount, and the other parent covers the remaining $2,000. If the paying parent later begins having the child 45 per cent of the time over a year, the calculation would move to the shared parenting rules instead.

This example is hypothetical and uses round numbers to show the method. Real cases often turn on what counts as income and whether an expense qualifies.

Common mistakes that cost parents money

Using the wrong year's table. Amounts calculated before October 1, 2025 may use older table figures. A new agreement or recalculation should use the 2025 tables.
Using gross pay instead of guideline income. Guideline income starts with "Total income" on the tax return and is then adjusted. Overtime, bonuses and investment income count; some items are deducted.
Treating section 7 expenses as automatic. Each expense has to meet the necessity and reasonableness test, and the parent claiming it should keep receipts.
Making informal side deals. A verbal promise to pay less, or to pay "when I can", is hard to enforce and hard to prove. Put agreements in writing and, where possible, file them.
Ignoring the disclosure deadlines. A parent who does not provide income information can have income imputed and may have to pay the other side's full costs (sections 22 to 24).
Waiting to claim. Courts can order support for past periods, but delay makes it harder. Our page on retroactive child support explains how courts approach it.

What to do this week

Gather the last three years of your personal tax returns and notices of assessment, plus your most recent pay stub.
Write down the current parenting schedule and count the overnights each parent has over a year.
List every child-related cost you pay: child care, health premiums, uninsured medical costs, school fees and activities, with receipts.
Look up the table amount in the official 2025 federal look-up using the paying parent's income and province.
If the other parent will not share income information, note the date you asked, in writing.
Book a free consultation with us to check the income figure and the special expenses before you sign anything.

Frequently asked questions

Do I have to go to court to get child support?

No. Parents can agree in a written separation agreement, and Ontario's Child Support Service can set up or update child support online in eligible cases. The other parent must respond within 25 calendar days of the date in their invitation letter, and the resulting notice is sent to the Family Responsibility Office for enforcement just like a court order.

Does the paying parent's new partner's income count?

The table amount is based on the paying parent's own income, not a new partner's. A new partner's income can become relevant if one parent claims undue hardship, because the standard of living test in Schedule II looks at the income of everyone in each household.

What if the other parent will not say what they earn?

The guidelines require income disclosure. If a parent does not comply, the court can make an order to produce the documents, proceed to a hearing, draw an adverse inference and impute income, and award costs. Each year after an order is made, the paying parent must also share updated income information; see yearly income disclosure.

What happens if child support is not paid?

Ontario's Family Responsibility Office enforces support orders and filed agreements. Our page on what happens if support is not paid explains the enforcement steps and what a parent who falls behind should do.

Is child support taxable?

Child support paid under an order or agreement made after April 1997 is generally neither deductible for the payer nor taxable for the recipient. Our page on support and taxes covers the details, including the different rules for spousal support.

Where is a child support case heard in Toronto?

A child support claim under the Family Law Act can be brought in the Ontario Court of Justice, which hears family cases in Toronto. Divorce and property claims belong in the Superior Court of Justice. Our page on the Ontario Court of Justice family courts in Toronto explains what to expect there.

Can child support be changed later?

Yes. Any change in circumstances that would produce a different amount under the tables is enough to vary an order based on the tables (section 14). Our article on changing child support payments walks through the options.

How is child support calculated in Ontario?