A child support dispute often starts with a practical question: does the amount being paid reflect the parents’ finances and the child’s needs? A salary increase, job loss, new childcare expense or change in parenting time can make an existing arrangement worth reviewing. The starting point is a reliable calculation supported by complete financial disclosure.
Child support is the child’s right. In Ontario, claims under the Divorce Act generally use the Federal Child Support Guidelines. Claims under Ontario’s Family Law Act use the province’s Child Support Guidelines, O. Reg. 391/97. The frameworks are similar, but the applicable legislation and the terms of any existing order or agreement matter.
How is child support calculated in Ontario?
The monthly table amount
For a child under the age of majority, section 3 of the Federal Guidelines generally starts with the applicable table amount, based on the paying parent’s annual Guidelines income and the number of children. The table ordinarily corresponds to the province where the paying parent lives. Guidelines income usually starts with total income on the income tax return, with the adjustments required by the Guidelines; take-home pay alone is not the measure.
The tables changed on October 1, 2025. Use the 2025 child support table look-up for periods from that date onward and the appropriate earlier tables for previous periods. An existing order does not automatically change because new tables have come into force.
The table is a starting point, not the complete answer in every family. For example, where each parent has at least 40% of parenting time over a year, section 9 requires consideration of both table amounts, the increased costs of shared parenting and the family’s circumstances. Equal parenting time does not automatically mean that no support is payable.
Special or extraordinary expenses
Section 7 permits an additional contribution toward qualifying expenses. These can include qualifying childcare related to employment, illness, disability or employment-related education or training, the child’s share of medical or dental insurance premiums, eligible uninsured health expenses, post-secondary education and certain extraordinary school or extracurricular costs.
An expense must meet the applicable legal requirements, including necessity and reasonableness. For health expenses covered by section 7(1)(c), eligible expenses must exceed insurance reimbursement by at least $100 annually. The usual sharing principle is proportional to the parents’ respective Guidelines incomes, after considering the child’s contribution and relevant subsidies, benefits and tax deductions or credits. It is not simply a split based on each parent’s net take-home pay, and not every activity or school expense qualifies.
What if the reported income does not tell the whole story?
Self-employment, fluctuating earnings and income held in a corporation can require a closer review. Under section 18, a court may include appropriate corporate income when the reported personal income does not fairly reflect the money available for support.
Section 19 also allows a court to impute income in appropriate circumstances, including unjustified intentional unemployment or underemployment, diverted income, unreasonable expense deductions or failure to provide required disclosure. This is an evidence-based assessment. A lower income does not, by itself, establish that a parent is avoiding support; reasonable health, education and childcare needs may be relevant.
When can child support change?
A change in income, parenting arrangements, qualifying expenses or a child’s circumstances may justify a review. Under section 14 of the Federal Guidelines, the variation test depends in part on whether the existing amount was calculated using a table. The change must be assessed against the applicable law and the existing arrangement.
Support does not necessarily end when a child turns 18 or finishes a particular school year. Continued education, illness, disability and other circumstances can affect ongoing entitlement under section 31 of Ontario’s Family Law Act or the Divorce Act’s definition of a child of the marriage. Review the child’s situation and the order or agreement before treating support as finished. For more on ongoing entitlement, see when child support ends in Ontario.
If your income falls, provide the relevant financial information promptly and seek to formalize an appropriate change. Depending on the case, this may involve a consent variation, a motion to change or an eligible recalculation service. Simply paying less does not amend an existing order.
Retroactive support and unpaid arrears
When income was understated or an increase was not disclosed, a court may order additional support for an earlier period. In Michel v. Graydon, 2020 SCC 24, the Supreme Court allowed a retroactive variation under British Columbia’s legislation even though the child was no longer dependent. The decision reinforces the importance of accurate disclosure, but an Ontario claim still requires analysis of the governing statute and whether it seeks an initial order or a variation.
In Colucci v. Colucci, 2021 SCC 24, an Ontario appeal, the Supreme Court explained the framework for retroactive reductions following a genuine material decline in income. Clear notice, supporting disclosure, timing and the family’s circumstances matter. Cancelling arrears that were properly owed is a separate, exceptional remedy requiring convincing evidence of an inability to pay now and in the future, even with a flexible payment arrangement.
The Family Responsibility Office (FRO) enforces support obligations; it cannot rewrite the amount in a court order. If you receive an enforcement notice or believe an order needs to change, address it promptly.
Get a clear assessment of your child support position
Whether you are seeking appropriate support for your child or responding to a claim that no longer reflects your finances, preparation matters. Gather the existing order or agreement, recent tax returns and notices of assessment, current income records, and receipts for disputed expenses.
Hashmi Law Group’s child support and parenting dispute services include advice on child support disputes and changes to support arrangements. Contact the firm to discuss your circumstances and the steps available to you.
This article provides general information about Ontario law and is not legal advice. The appropriate outcome depends on the facts, the applicable legislation and any existing order or agreement. Reading this article does not create a solicitor-client relationship.
