i use turbo tax. i used to say no to this question bcos i didn't realize that etrade was reporting incorrect cost basis. I assumed that whatever etrade was reporting on 1099-B would be accurate.
I fixed this for 2017 by editing the cost basis manually BEFORE filing. my question is about tax returns for 2016/2015/2014 tax year. what happens if i amend 2016 return? audit?