You can transfer the 2020 tax file to your new 2021 return, but you have to do it at the very beginning before you enter any new 2021 data at all. if you already started entering data, clear it and start over.
CLEAR AND START OVER
https://ttlc.intuit.com/questions/2586254-how-do-i-clear-and-start-over
How to transfer last year’s return? https://ttlc.intuit.com/questions/1900883
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