Each tax year has to be filed individually. Unfortunately, depending on which TurboTax software is needed, each return could have a separate cost involved. You have to open your 2021 return, and the interview at the beginning of the return will ask if you need to file another year where you will answer yes which will allow you to do your 2020 return first. Included below is the link to our free TurboTax software. If your tax situation is simple, you may be able to use our free version.