There is no discount for purchasing multiple tax years of the TurboTax software. Each tax year is a separate program.
For tax year 2017 you would 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.
Go to this website for the TurboTax 2018 CD/Download editions - https://turbotax.intuit.com/personal-taxes/cd-download/
If you choose to use the TurboTax online editions for tax year 2018 then go to this website - https://turbotax.intuit.com/personal-taxes/online/
