How do you open a .tax2018 file in windows 10

[Texas Roger]

You must have the 2018 TurboTax software program installed on your computer to open a .tax2018 file. If you have the program installed, you should not have any problem opening the file. You don't need the program installed to open a pdf file. 

[erobinett]

is this also true if you did the taxes and filed online with Turbotax.com

[Texas Roger · Accepted solution]

If the file you have is a .tax2018 file, you must have the 2018 TurboTax program installed on your computer to open it regardless of whether it was prepared using the online product or the desktop product.