Taking the time to do a comprehensive HR audit not only ensures compliance with applicable laws, but also provides the opportunity to improve the effectiveness and efficiency of HR practices to improve such things as employee performance, employee engagement or talent attraction and retention.  Best practice suggests scheduling an audit an once a year.  Scheduling regular annual audits to maintain the discipline of a regular review will prevent those “panic” audits (ones that take place only when a potential problem is brewing). Often such an audit is conducted after any significant event (e.g., new plans, management changes).