From answer.taxcut.com
How Do I: Copy a TaxCut file from a PC to a Macintosh computer?
To copy a PC Taxcut file to a Macintosh computer:
Copy the file to a PC-formatted floppy or other removable disk:
Put a PC formatted floppy or other removable disk (such as a CD or USB flash drive) into the appropriate disk drive of the PC that has the TaxCut file you wish to copy.
Open TaxCut.
Open the return that you wish to copy to the Macintosh.
Select the [File] menu and choose [Save As].
Click the [Browse] button and select the appropriate disk drive from the [Save in:] drop down, click [Save] and then click [OK].
Eject the removable disk and insert it into the appropriate disk drive.
Click the [Apple] menu, select [Control Panels], and choose [File Exchange].
In the [Extension] field type "Txx" where "xx" represents the last two digits of that tax year. For example, type "t04" for the year 2004.
Click the [Select] button at the bottom of the window.
Double-click the Macintosh hard drive, then scroll to and double-click the TaxCut folder.
Click the [TaxCutxx] application launcher where "xx" represents the last two digits of that tax year. For example, choose the [TaxCut t04] application launcher for the year 2004.
Click [Select].
Open the file normally.
Note: These instructions may not work on some older Macintosh OS versions.