I had a job during the tax year for which I received a T4 which I entered in the tax return. I also attended post-secondary school for which I received a T2022A. Why does my refund amount decrease after I fill out the form for my tuition details?

If your net income falls under a set threshold set by CRA (as an individual or as a family), you would be eligible for Canada Workers Benefit (CWB). However, one of the requirements thatmakes you ineligible to receive this refundable credit is full-time enrolment at a designated educational institutions for more than 13 weeks, unless you have an eligible dependent.