I filed offline via TurboTax in 2021 so my tax history from 2019 and 2020 did not carry over. Any way to correct this?

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@ mnfish wrote:

Okay, thanks. I have already filed my 2021 taxes using TT desktop so I gather it's too late to do anything. FYI, when I log into Turbo Tax online it asks if I want to file my 2020 taxes which obviously I already did last year via desktop. No mention of my 2021 file online. I don't recall TT asking if I wanted to download 2020 when I started my taxes this year.

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The desktop and online products are completely independent and do not communicate with each other.  If you used desktop 2021 software this year, then your Online TurboTax account will have no evidence of a 2021 desktop return in the online account.   If your online account is mentioning finishing a 2020 return, then maybe you started a 2020 online return last year then decided to ultimately use 2020 desktop software instead. 

It's all moot if you already efiled your 2021 return and the efile was accepted, or if you printed and mailed it. 

For future reference, here's what normally occurs.  I don't know if you use Windows PC or Mac.    I use Windows; the Mac method may be slightly different.

In the Windows version, when one launches the TurboTax program and selects to begin a new tax return, the software will automatically churn and search one's computer looking for a *.tax2020 data file residing on the computer.  If/when it finds it, it then asks if you want to transfer it into the 2021 return.   If it doesn't find the 2020 data file, but you know the location, a user can tell TurboTax the location of the *.tax2020 data file, then the transfer proceeds.

I'm not sure what prompted your original question; i.e., why you were asking about transferring the 2020 data into an already-filed 2021 return.   Were you trying to correct something in the filed 2021 return?  Or were you asking just for the sake of continuity of data year after year?

If you efiled your 2021 return and it was accepted, or if you mailed the 2021 return, the only way to make any changes in it is by preparing a formal amended return Form 1040X.   You wouldn't be able to transfer the 2020 data file in that situation, either.