Also, after each work session I save another copy of the *.taxYYYY data file on external media such as a flash drive. For instance, last fall there was an infamous Windows update that caused data loss of items in some users' documents folder, etc. for various software programs. And hard drives can also fail.
TurboTax for Windows "should" prompt you and ask if you want to save the file if you try to close it using the top right X. But a few users have reported that it didn't. I don't know if that prompt exists in the Mac program or not.
