I discovered that I did not properly account for depreciation and need to file amended returns for 2018 and 2019. The change is pretty straightforward and I am confident in my ability to properly file a 1040-x through TT. Once I work through 2018, can I submit my 2019 1040-x electronically, and then can I submit my 2020 electronically or will I need to file them through the mail as well?