I had the same question and looking at the thread, looks like I cannot file Amendment online(e-file). However, I went through Amend 2019 return on my Desktop TurboTax and choose file by Mail and I get a Warning saying my my return was already filed ( I assume that from my initially filing). When Saved the Copy Federal "Electronic Filing Instructions for your 2019 Federal Amended Tax Return" Do not provide any instructions for Mailing. Also I am not sure if I can use the forms generated to Mail. Can you please clarify?
Thanks
