Each tax year is a separate TurboTax program.
To complete and file a prior year tax return, 2016 thru 2018, using TurboTax you would need to purchase, download and install on a personal computer, Win or Mac, one of the prior year desktop program for each year required from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
Prior year tax returns can only be printed and mailed, they cannot be e-filed.
