I have contacted the support. It was determined that there is in fact an error in the 9369 box in the T776 form, which is wrongly applying 100% of gross rental income in order to calculate the personal Net rental income, even when the co ownership is marked as 50% only. The formula should be: 50% of gross rental income minus 50% of total expenses, while it seems to be 100% of gross rental minus 50% of expenses, producing much higher amount which is transferred into T1 form and results in higher total general income amount.
I am using Turbo Tax for years at this point, and just accidentally spotted this error. It is deeply disappointing that the program cannot really be trusted to properly calculate your taxes. The whole idea of using this automated tool it is to be sure you're not making a mistake! I am going to look into the same form in 2024 version to confirm whether the same problem occurs there as well.
