One of the most common misconceptions in Canadian family law is that child support automatically stops at age 18. It does not. The Divorce Act uses a specific legal definition — "child of the marriage" — that can extend support obligations well beyond the age of majority in many circumstances. This article explains the two-limb definition, the age of majority by province, how courts assess adult child dependency, and what happens to the calculation.

The "Child of the Marriage" Definition

Under section 2(1) of the Divorce Act, a "child of the marriage" is a child of two spouses (or a child of whom one is the parent and the other stands in the place of a parent) who meets either of two tests:

Both limbs must be assessed as of the relevant date — typically the date the support application is heard. A child who was dependent at separation but has since become self-sufficient no longer qualifies.

Age of Majority by Province

The age of majority is not uniform across Canada. It varies by province and territory:

The age of majority determines when limb (a) of the definition no longer applies. After that age, the child must qualify under limb (b) — unable to withdraw from the parents' charge — for support to continue. Under the Divorce Act, the federal definition governs for divorcing couples; under provincial family law legislation, the provincial age may set different rules for common-law separations.

University Students — The Most Common Scenario

The most common situation where support continues past the age of majority is a child attending post-secondary education. "Pursuit of reasonable education" under limb (b) has been interpreted broadly by Canadian courts, but it is not unlimited. Courts consider a range of factors:

Illness and Disability

Support for an adult child with a serious illness or disability can continue indefinitely. The test is whether the child is unable to become self-supporting due to their condition. This can include physical disabilities, mental health conditions, developmental disabilities, and chronic illnesses. There is no age limit — a parent may have an ongoing support obligation for an adult child with a permanent disability.

How Support Is Calculated for Adult Children

When a child qualifies under limb (b), the standard table amount under section 3 may still apply — but courts also have discretion under section 3(2)(b) to set a different amount based on the child's actual needs, means, and circumstances. In practice, courts often consider the child's own income and contribution capacity, the cost of tuition and living expenses, and the parents' respective financial positions.

For an adult child living away from home at university, the calculation may look different from a minor child living in a parent's household. Some courts have ordered a proportional contribution from each parent toward the child's actual education costs (tuition, books, living expenses) rather than the straight table amount. Others have applied the table amount on the basis that it adequately covers the parent's contribution.