Mine was rejected as well. It seems that the software put "Covid Cares Act" on line C of 8915-F which I believed caused the rejection. It should be blank if you checked the box for "Was this a Coronavirus-related distribution reported in 2020 check here" which it was. It seems that any entry for line C has to be a FEMA number in a specific format. I'm using the online version so I can't edit the form directly but I think deleting that would fix it. If I am mistaken please let me know? If I'm right, anyone else figure out a way to fix it using the online version?
