If the court finds that an adult child is still a “child” or a “child of the marriage” for support purposes, the court must then determine the amount of support to be paid. https://onyxlaw.ca/calculating-income-child-support-income-fluctuates-year-year/ Section 3(2) of the Federal Child Support Guidelines governs the amount of child support for a child over the age of 19:
3 (2) Unless otherwise provided under these Guidelines, where a child to whom a child support order relates is the age of majority or over, the amount of the child support order is
(a) the amount determined by applying these Guidelines as if the child were under the age of majority; or
(b) if the court considers that approach to be inappropriate, the amount that it considers appropriate, having regard to the condition, means, needs and other circumstances of the child and the financial ability of each spouse to contribute to the support of the child.
What that means is that the court can order the Table amount, or, under Section 3(2)(b), the court can exercise its discretion to order child support in a lesser amount. Whether the child is still living at home while attending school is a significant factor here.
Bear in mind that the court can also order proportionate sharing of a child’s post-secondary education expenses in addition to basic child support. Expenses include reasonable costs for tuition, textbooks, accommodation, and food. An adult child has an obligation to contribute towards their own expenses, so the court will deduct any contribution from the child before ordering sharing of the expenses in proportion to the parents’ incomes.