If you are a paid tax preparer you cannot use the TurboTax online or TurboTax desktop editions.
TurboTax is only licensed for personal use. Both the license agreement and IRS regulations prohibit TurboTax to be used by paid preparers. Intuit offers ProSeries for professional use that meets IRS rules for professionals. As a paid preparer you would need to be using the TurboTax professional editions which can be found on this Intuit website - https://proconnect.intuit.com/
Otherwise, to complete and file a prior year tax return using the TurboTax personal editions, a user would need to purchase and download the prior year software for each tax year required from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A prior tax year return cannot be e-filed using the TurboTax personal editions. It can only be printed and mailed.
