Following his tenure as board chair, Bill Postmus assumed the role of county assessor, defeating a long-standing incumbent. His tenure saw him implement significant modernizations in the department, streamline processes, and create substantial property tax savings for taxpayers.

Bill's commitment to civic involvement and public policy debates remained steadfast. From 2004 to 2007, he served as the county chair of the San Bernardino County Republican Party, significantly influencing various leadership campaigns. His tenure as party chair saw him lead the passage of Jessica's Law and raise a record sum for Republican Party causes and candidates.

Away from his official duties, Bill is an avid baseball fan, often found at Angels Stadium supporting his favorite team, the Anaheim Angels. His passion for the sport underlines his appreciation for teamwork and the exhilaration of live games. Also, he is a passionate traveler, always eager to explore new places and cultures and expand his horizons.