Document.SaveFormat (Word)

Returns the file format of the specified document or file converter.

The SaveFormat property will be a unique number that specifies an external file converter or a WdSaveFormat constant. Use the value of the SaveFormat property for the FileFormat argument of the SaveAs2 method to save a document in a file format for which there isn't a corresponding WdSaveFormat constant.

If ActiveDocument.SaveFormat = wdFormatRTF Then 
 ActiveDocument.SaveAs FileFormat:=wdFormatDocument 
End If