The only way to open a TurboTax .tax file is with the CD/Download TurboTax software for the corresponding year. For example, to open a .tax2019 file you need the TurboTax software for 2019.

If you really have a .tax file, not .tax20xx, that is a very old file, from 2007 or earlier. TurboTax files for 2008 and later have the year included in the file name extension, such as .tax2019.

It does not help because the question was not completly answer

I have .tax files from the nineties that I would like to open and then convert into PDF files for storage.  Is there any way to do this without having the original CD disks for each year?

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@tjmokry wrote:

I have .tax files from the nineties that I would like to open and then convert into PDF files for storage.  Is there any way to do this without having the original CD disks for each year?

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No, and even if you had the CD's, they would be useless unless you could get updates that are not supported any longer for tax years 2015 or before.   Also .tax files cannot be opened if they contain state information unless the state software is also installed that is no longer available.