The fourth stage of the reform was voted in by the Bundestag on December 16, 2003 and by the Bundesrat on July 9, 2004, to take effect by January 1, 2005.
Den fjerde fase af reformen blev stemt ind af Forbundsdagen den 16. december 2003 og af Forbundsrådet den 9. juli 2004 og tog effekt den 1. januar 2005.