The software told me the amount on line 121 "may" have come from my T5 (I didn't have a T5), bank interest (went back and checked that section - $0) or box 25 on my T3 slips. I triple checked the amounts on box 25 and the number I got was exactly $20 less than the amount the software entered on line 12100. Where could this additional $20 have come from, and why can't this software show me exactly where it got all of the source data to enter into these line items on my T1?