Child Support Calculator Ontario: What the Result Leaves Out

You enter an income, the number of children and a province, and a number appears. That figure can be a useful starting point, but it is rarely the whole story.

This article explains what a typical calculator result leaves out and which details are worth checking before you rely on it.

What a calculator is doing

The basic amount of child support is the table amount for the number of children, plus any special or extraordinary expenses under section 7. The table amount depends on the paying parent's annual income, the number of children and the province where the paying parent lives. A simple calculator generally only gives you the first part.

To give a sense of scale, the 2025 Ontario table for one child is $450 a month at a payor income of $50,000, $695 at $75,000, $932 at $100,000 and $1,327 at $150,000. For two children the same income points give $744, $1,144, $1,517 and $2,135. Each income band adds a percentage of income above its starting point, so a figure inside a band is slightly higher than the start-of-band amounts.

Check which tables the tool uses. Updated federal tables took effect on October 1, 2025, and the 2017 tables apply to support owed from November 22, 2017 to September 30, 2025.

Calculators also tend to assume a minor child. For a child who has reached the age of majority, the court may apply the Guidelines as if the child were a minor, or set the amount it considers appropriate if that approach seems inappropriate.

Extras the number may not include

Section 7 covers child care because of a parent's employment, illness, disability or education, the child's share of medical and dental premiums, health expenses above insurance by at least $100 a year, extraordinary school and extracurricular costs, and post-secondary education.

• These are paid on top of the table amount.
• The court considers whether each expense is necessary in the child's best interests and reasonable given the family's means and spending before separation.
• The spouses share the expense in proportion to their incomes, after deducting any contribution from the child.
• For child care, subsidies, benefits and tax deductions or credits are taken into account first, so the after-tax cost is what gets shared.

Parenting time and hardship change the approach

If each parent has at least 40% of parenting time over a year, the court looks at both parents' table amounts, the increased costs of shared parenting and each parent's and child's circumstances. There is no automatic formula.

Where there is more than one child and each parent has the majority of time with at least one of them, support is the difference between the table amounts each would otherwise pay. A calculator set up for one primary home will not reflect either arrangement.

A court may also order a different amount if a spouse would otherwise suffer undue hardship, for example because of unusually high debts reasonably incurred to support the family or legal duties to support other children. The claim must be denied if the household of the spouse claiming hardship would have a higher standard of living than the other spouse's household.

Income is rarely as simple as one number

Income for child support starts from total income on the T1 General tax return and is adjusted under Schedule III. Several situations can make the figure you typed in the wrong one:

If the payor earns over $150,000, the court may order the full table amount or the table amount on the first $150,000 plus an amount it considers appropriate above that.

What to do next

Use a calculator for a rough range, then test it against your real facts. Ontario's online Child Support Service can set up or update support without court, for a non-refundable $80 each time, but it is not available in many situations, including shared or split parenting, a self-employed payor or income over $150,000 or under $12,000.

If your order was made before October 1, 2025, the 2025 tables do not change it automatically, but a difference between the old amount and the 2025 table amount may count as a change in circumstances that lets a parent ask for an update.

• Confirm the tool uses the 2025 tables for current support.
• Gather three years of tax returns and notices of assessment.
• List section 7 costs and any subsidies or tax credits.
• Track the real parenting schedule over a year.
• Ask a family lawyer to review the figure before you sign or file anything.

Frequently asked questions