The invention relates to an end plate for filter material (10) for filtering a liquid, particularly a hydraulic oil, having a through opening (11) for filtered liquid, which is surrounded by a sealing ring (20) for a connecting piece, and a cover (12) for the filter material (10). The invention is characterized in that the sealing ring (20) delimits a free space (13) for accommodating an anti-rotation lock (14) of a switch (15) and/or a bypass valve (16) of a filter system (30). Furthermore, the invention relates to a filter element, a filter system and a method for filtering liquid.