To purchase one of the TurboTax desktop CD/Download editions for tax year 2019 go to this website - https://turbotax.intuit.com/personal-taxes/cd-download/
For prior year software, 2018 thru 2016, go to this TurboTax website to purchase and download the software - https://turbotax.intuit.com/personal-taxes/past-years-products/
