The U.S. Supreme Court, in the widely watchedIntelcase, agreed with former employees that an employer cannot shorten the time period over which plan participants can sue by simply posting relevant information online or sending information in the mail. In most cases, plan participants have six years to bring a lawsuit for fiduciary breach. However, that window is shortened to three years from the date the participant had "actual knowledge" of the fiduciary violation. For more information on investment diversification requirements for 401(k)s, visit Tax Facts Online.