The program doesn't work that way.
With the online version, you can only e-file the current tax filing year. As of the date of this post, the current tax filing year is 2020. You flat out can not use the online version to complete and file a prior year tax return.
With the desktop version you have to purchase the program for the tax year you want to file, install it on your computer, and then use that program to prepare your tax return.
You can purchase the CD/Desktop version of TurboTax for whatever tax year you need up to a maximum of 3 years back, at https://turbotax.intuit.com/personal-taxes/past-years-products/ Make *SURE* you click the link for the tax year you need to purchase. If you purchase for the wrong year, you own it.
Take note that a prior year tax return can not be e-filed. The IRS says so. You have to print, sign and mail your return to the IRS. Same holds true for state, if you are required to complete a state return for a prior tax year.
