Can I e-file someone's 2020 return this year or is it past the three-year mark?

[hgeiman]

The threshold to e-file in ProConnect is three years. I know 2020 is numerically over three years ago, but since the following year is when taxes are filed, is it still within the three-year threshold?

[IRonMaN]

No can do

[deb4]

The due date of the 2020 return was 4/15/21.  You have 3 years from the due date of the return to file an amended return.

[George4Tacks · Accepted solution]

You are allowed to file the current year being processed (2023) and two prior years (2021 -2022). Those are the three years that can be e-filed. Paper is not that much slower than e-file (according to what IRS publishes). 

You almost got the amendment rule right, but that is not the e-file rule. See page 3 https://www.irs.gov/pub/irs-pdf/i1040x.pdf