Files with fef file extension might be found as part of old German accounting software called Steuer2001.
FEF file extension - Steuer2001 data
What is fef file? How to open fef files?
File type specification:
The fef file extension seems to have been used in the past in Steuer2001 program, which was probably a German accounting software.
Most likely some old format without support. No further information could be found.
This fef file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.