Convert TAX to TT12

The TAX and TT12 are file extensions used by tax preparation software called TurboTax that is available for Mac and Microsoft Windows. You can certainly  view content of these files in the TurboTax, but there is no reason to convert them, because it is the same file format, only with different file extension that indicates year of tax return, which means tax to tt12 conversion actually does not make sense much.