[blihp]

QuickBooks and GnuCash handle the accounting, which supplies the data needed for your taxes. However, they won't spit out your tax forms as that's a separate task and not likely something open source is going to tackle anytime soon given how convoluted, arbitrary and constantly changing tax laws can be. Most open source developers would rather go in for multiple elective root canals before dealing with that.

Yes, it's possible to do your own taxes but it's a headache the first time or two you do it. I have never found any open source software to help with it beyond things like LibreOffice Calc to do various tax worksheets.