Since filed returns are locked (unable to edit), you can make a copy instead. On the Return Manager screen, choose the option to copy your filed return. Be sure to label your return appropriately as a test return (to avoid confusion in the future).
Suggestion did NOT help. I cannot change numbers on the copy to see what would happen to my balance owing.
Thank you for the reply. Unfortunately, you are correct. The function is currently unavailable but is scheduled for release next month (mid-April). Please try again then. My apologies for the delay.
Has this still not been changed? Is there any way to use 2017 tax return to tax plan for 2018?
The option to change entries on a filed return has not been enabled yet unfortunately. If you would like to run a test using the 2017 version of TurboTax, you may start a new return. There's no need to pay as you won't be filing so it's free to "play around" in a new return if you wish.