Install the program as normal (download can be found here TaxCalc 2004)
NOTE - Do not choose to run the program when the installer finishes.
TaxCalc 2004 can now be opened.
IMPORTANT TaxCalc have not carried out regression testing on this program on platforms later than Windows XP and cannot guarantee the functionality of the 2004 product in Vista, Win7/8 or 10.
Also please note that Windows XP and Vista are no longer supported by Microsoft and are considered 'unsafe' to use for security reasons