How to change a child support order in Ontario
A child support order in Ontario can be changed when there has been a material change in circumstances — most commonly a real income change or a change in parenting time. Until a court (or the Ontario Child Support Service, in some cases) actually changes the order, the original amount applies. You cannot just start paying a different amount. Below is the actual sequence Ontario uses, in order. Run it the right way and a routine variation costs little and takes weeks. Skip the steps and you create arrears that do not disappear.
The Family Law Rules govern Motions to Change. Section 17 of the Divorce Act governs variations of support under divorce orders; section 37 of the Family Law Act governs non-divorce orders.
Step 1 — Confirm there is a material change
A material change in circumstances is the legal gatekeeper. For child support, the common qualifying events are a meaningful income change (up or down, but enduring — not a one-off bonus), a child aging out of support, a change in parenting time that affects the Federal Child Support Tables calculation (for example, switching from sole to shared parenting), or a new child the payor is now supporting. What does not qualify: a temporary dip in income that you can ride out, a personal preference to pay less, a disagreement with how the recipient is spending the money. See the material change test for the detail.
Step 2 — Recalculate the support
Run the new number before talking to anyone. The Cairn free calculator gives you the Federal Child Support Tables amount in two minutes — table amount based on the payor's gross income, plus your share of section 7 expenses. Write down the current order amount, the proposed new amount, and the date the change should be effective from (usually the date the change in circumstances occurred). Numbers in hand makes every next conversation faster.
Step 3 — Try agreement first
If the change is well-supported by the numbers, write to the other parent (in plain language, in writing) proposing the new amount and effective date. Most reasonable separation files settle variations through this informal route — the spouses sign a written amendment, both take Independent Legal Advice, and the amendment is filed with the court and the FRO. For Federal Child Support Tables amounts where the only variable is the payor's income, you can also apply to the Ontario Child Support Service for an administrative recalculation. The Child Support Service handles routine annual updates faster and cheaper than court.
Step 4 — If agreement fails, file a Motion to Change
Use Form 15 — Motion to Change. The form sets out the existing order, the material change, and the proposed new amount. File supporting documents: three years of T4s, recent pay stubs, recent Notice of Assessment, and any documents showing the change (a termination letter, a new tax return showing the lower income, evidence of the parenting-time change). Serve the other parent. They have 30 days to respond. From there the process is the same as any other family court matter — possibly a case conference, possibly a motion, possibly a settlement before either.
Step 5 — Keep paying the existing order in the meantime
Until the change is granted, the existing order is the binding amount. Pay it. The FRO will continue to enforce the original amount, and stopping payments while a variation application is pending creates arrears that the variation order may or may not retroactively cancel.
What does not justify a change?
A temporary income dip you can manage. Disagreement over how the recipient is spending the money — the order does not police that. A new partner contributing to the household. A general feeling that the original amount was too high. None of these meet the material-change test, and bringing a motion on weak grounds wastes money and prejudices your file.
Where Cairn helps next
Cairn's free Ontario child support calculator gives you the table amount in two minutes - the number you need before any motion, agreement, or recalculation. No email, no signup.
- Your Ontario child support number, calculated under the Federal Child Support Tables
- The numbers for both current and proposed parenting arrangements
- A six-page PDF you can email to yourself or your lawyer
Frequently asked questions
When can I change my child support order in Ontario?
When there has been a material change in circumstances - a meaningful, enduring change since the original order. Common qualifying events: significant income change up or down, a child aging out of support, a change in parenting time that affects the table calculation, or a new child the payor now supports. Temporary changes, preferences, or disagreements with how the recipient spends the money do not qualify.
What is a Motion to Change in Ontario family law?
Form 15 - the court form used to vary an existing support or parenting order. It sets out the original order, the material change, and the proposed new terms. Filed at the same court that made the original order. The other parent has 30 days to respond. The process is similar to any other family court matter from that point - possibly a case conference, possibly settlement, possibly a motion.
Can I use the Ontario Child Support Service instead of court?
For routine income-based recalculations of Federal Child Support Tables amounts, yes. The Ontario Child Support Service is an administrative recalculation service that handles annual updates based on the payors income. It is faster and cheaper than court. Eligibility is restricted - the service handles routine table-amount cases, not parenting changes or complex incomes.
Can I stop paying child support while my variation is pending in Ontario?
No. Until a court (or the Child Support Service) actually changes the order, the original amount applies. The Family Responsibility Office continues to enforce it. Stopping payments while a variation application is pending creates arrears that the variation order may or may not retroactively cancel. Keep paying the current order in the meantime.
How long does it take to change a child support order in Ontario?
Through the Child Support Service: weeks to a few months for routine recalculations. Through a Motion to Change in court: typically four to twelve months from filing to order for an uncontested variation. Contested variations involving disclosure fights or parenting-time disputes can take longer. Bringing the motion promptly when the change occurs makes retroactive cancellation of arrears easier to argue.