How to Modify a Child Support Order in Ontario

Life Changes — and So Can Child Support

A child support order is not meant to be set in stone forever. Incomes go up and down, parenting arrangements evolve, and children’s needs change as they grow. Ontario law recognizes this reality and provides a clear process for modifying child support orders when circumstances change.

This guide explains when you can change a child support order, how the process works, and what to do if the other parent disagrees.

The Legal Standard: Material Change in Circumstances

To modify an existing child support order in Ontario, you must demonstrate a “material change in circumstances” — meaning a change that, if it had been known at the time of the original order, would likely have led to a different result. Not every change in life qualifies. The change must be significant and not anticipated when the original order was made.

Common Reasons to Modify Child Support

• A significant increase or decrease in the payor’s income (typically a change of 10% or more)
• A change in the parenting arrangement (e.g., the child moves primarily to the payor’s home)
• A new child being born to one of the parents
• A child becoming eligible for adult child support (age of majority and pursuing education)
• A child no longer being a “child of the marriage” — for example, becoming financially independent
• Significant new special or extraordinary expenses (such as private school, orthodontics, or competitive sports)
• Loss of employment, disability, or retirement of the payor

Two Routes: Administrative Recalculation or Court Application

Administrative Recalculation through CSROS

Ontario has a Child Support Recalculation Service (CSROS) that can update child support amounts annually based on the payor’s updated tax return — without going to court. This service is available where the original order or agreement specifically provides for recalculation. It is fast, free, and simple.

Court Application or Motion to Change

If the change you need is more substantial — or your order is not eligible for administrative recalculation — you will need to file a Motion to Change in family court. The process generally involves:

• Filing a Motion to Change (Form 15)
• Filing a Change Information Form (Form 15A) and updated financial disclosure
• Serving the other parent with the motion
• Attending case conferences and any required court appearances
• Either reaching agreement or proceeding to a hearing

Changing Support by Agreement

If both parents agree to a change, you can document it in a written amending agreement and, where appropriate, file a consent Motion to Change with the court. This is far less expensive and stressful than a contested motion. An experienced family lawyer can ensure that any agreement is properly drafted, fair, and enforceable.

Retroactive Changes

In some cases, you can ask the court to make a child support change retroactive — meaning support is adjusted back to an earlier date. The Supreme Court of Canada has set out factors that courts consider in retroactive cases, including the reason for any delay, the conduct of both parents, the child’s circumstances, and any hardship caused. Retroactive variations are most often available when a parent has under-reported or hidden income.

Special and Extraordinary Expenses (Section 7 Expenses)

Beyond the basic table amount of child support, parents share “section 7 expenses” in proportion to their incomes. These include things like child care, post-secondary education, healthcare costs not covered by insurance, and extracurricular activities. If a new section 7 expense arises — or an existing one significantly increases — this can also support a motion to change.

Acting Quickly Matters

If your income has dropped significantly, it is critical not to delay. Child support arrears continue to accumulate unless and until the court orders a change. Asking for a variation as soon as your circumstances change protects you from building up arrears you may not be able to pay back.

Why This Matters to You

Child support is one of the most important financial obligations parents have. Whether you are paying or receiving, ensuring that the amount accurately reflects current circumstances is essential — both for the child and for the parents. Trying to handle a complex variation on your own can lead to unfavourable results.

The Toronto child support lawyers at Soica & Associates help parents seek or resist variations of child support orders.

This article is intended for general informational purposes only and does not constitute legal advice. Laws may change, and outcomes vary depending on individual circumstances. Please consult a qualified family law lawyer at Soica & Associates for guidance specific to your situation.