Under the Divorce Act, if you are a payor of child support, your obligation to pay child support, including post secondary education costs, may continue after your child becomes 18 years of age, if your child attends a university or college, full time, with passing marks until a first degree (sometimes, longer in special circumstances). The Family Law Act (which applies to unmarried couples) puts a specific time limit on child support for adult children at 22 years of age.
If your child resides with the other parent, you will continue to pay both Section 3 (basic child support) and your share of Section 7 expenses. If your child is away from home to attend a university or college outside home, then the support is determined based on the specific circumstances of the case.
An adult child is expected to reasonably contribute to their own education, by working part-time during school if practicable or working during summer time.
Divorce Act (Canada), RSC 1985 c. 3
Family Law Act, S.A. 2003 c. F-4.5