Yes, you can import a prior year tax data file from TurboTax Desktop into TurboTax Online. You can only import one year to carryover the data.
You cannot upload all of the files to the TurboTax Online cloud.
You would want to do this before you start entering data for your return; although, you need to choose a version and continue into the tax preparation.
1. Click on My Account in the top center
2. Click on Tools
3. Click Transfer last year's TurboTax return from your computer from the list at the bottom
4. Click Continue if prompted
5. Browse for the .tax20XX file
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