Her share of tuition for post secondary school

A: tuition, books , and monthly living expenses are all s.7 expenses under the Child Support Guidelines which are subject to sharing in proportion to each parent's income (& subject to the child's ability to contribute via student loans, bursaries, scholarships and the students part time income). Assuming the child is 19 or more and is not living at home, you would no longer pay basic monthly child support to the mother - you would only pay your proportionate share of all of the above expenses. Though you need a written agreement or a court order to put this into effect.