Can I do some changes in tax return if I completed it but didn't file it yet? ( didn't mailed it?)

[mesquitebean]

As long as you have not actually filed (haven't efiled and haven't mailed) your return, you can open it back up to keep working on it.

• Log in and go to your 2016 Tax Timeline.
• If TurboTax thinks you are finished, there will be no orange "Take me to my return" button.
• So in that case, scroll down to "Some things you can do."
• Choose "Add a State."  (you don't really add one; that's just to get the return to open up.)
• Once the return is open, you can work on it and make any changes prior to filing.
  
  

NOTE:  Do NOT use this method to open a return to make changes/edits to an already-filed return (one that has actually been mailed or efiled.)   If you later need to make changes to an already-filed return, you have to go through the formal amending process, and your return must start off exactly as originally filed.