in IRS publication 4164, it says this:
1.4.1 Current and Prior 2 Tax Years are Accepted
When a new tax form type is added to the MeF platform, tax returns will be accepted for the first Processing Year only.
• In Processing Year 2023, MeF will accept TY2022, TY2021 and TY2020 returns for Form 1040
• In Processing Year 2023, MeF will accept TY2022, TY2021 and TY2020 returns for Form 1040-NR
• In Processing Year 2023, MeF will accept TY2022, TY2021 and TY2020 returns for Form 1041
As subsequent Tax Years are added to the system, MeF will accept the current year and two Prior Tax Years. Tax Years beyond the two Prior Years cannot be filed through MeF.
When a tax form type is removed from the MeF platform, tax returns will be accepted through the final Processing Year only
So it seems that it is possible to e-file 2021 taxes in 2023, but what is not clear to me is whether turbotax is part of the MeF system or not ?
