Your 2019 data can be transferred to a 2020 return when you begin to use the CD/download software. Any time you transfer the previous year to the new return you must do that before you enter any other data.
How to transfer last year’s return? https://ttlc.intuit.com/questions/1900883
Be aware that when you use desktop software the tax file and pdf are stored only on your own hard drive--they are not stored online. Save and back up---and back up to a flash drive, etc. too.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**