You can use either the TurboTax online or desktop editions to complete and file a 2018 tax return.
Go to this website for the 2018 online editions - https://turbotax.intuit.com/personal-taxes/online/
Go to this website for the 2018 desktop CD/Download editions - https://turbotax.intuit.com/personal-taxes/cd-download/
A 2018 tax return can be e-filed at any time up through October 15, 2019. After that date the 2018 tax return can only be printed and mailed.
If you choose to use TurboTax to complete and file a 2017 tax return then you will need to purchase, download and install on a personal computer one of the 2017 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2017 tax return can only be printed and mailed, it cannot be e-filed.
