Put this code into the Codemodule of the ThisWorkbook Object.
It will save a dated/timed copy whenever you save. It can be modified to only save a dated copy,
overwriting the previous saved copies from that day...
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
If SaveAsUI Then Exit Sub
MsgBox "I'm about to save a dated copy...."
Application.EnableEvents = False
ActiveWorkbook.SaveCopyAs Filename:= _
Replace(ActiveWorkbook.Name, ".xls", _
" BU " & Format(Now, " yyyy-mm-dd hh-mm") & ".xls")
Application.EnableEvents = True
End Sub
HTH,
Bernie
MS Excel MVP