You need the 2018 software program to open a 2018 tax file, if you did not save it as a pdf. Do you only have the .tax2018 file? Unfortunately, the software for 2018 is no longer available so if you only have a tax file, you will not be able to open the file on your computer. There is a service---which is NOT part of TurboTax----called taxprinter.com which can print old returns for a fee.
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