How do I change an existing child support order in Ontario?

A child support order can be changed through a formal court process called a motion to vary. To succeed, you must show that there has been a material change in circumstances since the order was made — something that, had the court known about it at the time, would have led to a different order. Common examples include a significant increase or decrease in the payor's income, a change in the child's residence, the child starting or finishing post-secondary school, or the payor losing employment.

You can also vary an order by reaching a new written agreement with the other parent, which can then be filed with the court to become enforceable as an order. Many parents update support informally when incomes change, but this creates risk — an unregistered agreement does not bind the Family Responsibility Office (FRO), which enforces court orders in Ontario.

It is generally good practice for payors to request a formal review whenever their income changes significantly, and for recipients to do the same if the payor's income has increased. Annual income disclosure is required under the Guidelines to facilitate exactly this. A lawyer can file a motion to vary on your behalf or help you draft a variation agreement that is properly structured and court-filed.