The .tax2016 file is the TurboTax data file version of your return. It is required to open your return if you ever needed to use the desktop program to amend your return in later years, so it is good to keep a copy of this just in case, but you won't be able to open it without the TurboTax CD software installed on your computer. So, it is your return, but you can't open it on its own.
The .tax2016 file is the TurboTax data file version of your return. It is required to open your return if you ever needed to use the desktop program to amend your return in later years, so it is good to keep a copy of this just in case, but you won't be able to open it without the TurboTax CD software installed on your computer. So, it is your return, but you can't open it on its own.