Your amount owing might have gone up because your student status made you ineligible for the Working Income Tax Benefit. You cannot claim the WITB if you were enrolled as a full-time student for more than 13 weeks in the year, unless you had a child under 19. You may not be seeing your tuition fees on your tax summary if you did not need them to reduce your taxes payable. The tuition credits will be carried forward automatically for you to claim in a future year.