Who qualifies as a 'child' for child support purposes under the Ontario Guidelines?

Under the Federal Child Support Guidelines (for divorcing parents), a "child of the marriage" is a child under 18, or a child who is 18 or older and unable to withdraw from parental charge due to illness, disability, or other cause — including pursuit of full-time education. Ontario's Children's Law Reform Act uses similar language for unmarried parents.

Biological children and legally adopted children clearly qualify. In some cases, stepchildren may also qualify if a stepparent stood in the place of a parent and the court finds it appropriate to order support. Children born during the relationship who are recognized as children of both parties also qualify regardless of biology if both parties acknowledged the parental relationship.

The definition deliberately extends past age 18 to protect children who remain dependent — most commonly post-secondary students, but also adults with serious disabilities or health conditions that prevent self-sufficiency. There is no fixed upper age in the legislation; each case is fact-specific. Courts consider whether the child is genuinely dependent and whether continuing support is reasonable given both the child's circumstances and the parents' means. If you are unsure whether a particular child or adult qualifies, a lawyer can assess the specific situation against the applicable legislation.