My self employment (and only)income is only $8000, but when I add my T2202A tuition tax credit, my return goes from a refund of $800 to owing $547. What am I doing wrong?

Ok so I think I figured out that the CWB disappears when I enter the tuition credit, as full time students are not eligible for the CWB. However, as my net self employment income is only about $8000,  shouldn’t my amount owing be $0? 

Not necessarily, TurboTax will use what it can to bring down the amount owing. There are times you may still end up owing. 

Thank you for choosing TurboTax.