Noguez was arrested at his Los Angeles home Wednesday on bribery and corruption charges after a yearlong investigation, during which he has denied wrongdoing.
County District Attorney Steve Cooley announced Noguez, along with an aide, Mark McNeil, and campaign contributor Ramin Salari, had been charged in the alleged scheme involving reduced property taxes in exchange for campaign contributions.
Court documents allege Noguez cost the county $1.16 million in lost revenue and Cooley said the figure was "probably growing."
McNeil and Salari were also arrested Wednesday, the Los Angeles Times reported.
"Los Angeles County voters and taxpayers deserve honest, hardworking elected and appointed officials who will serve the best interests of the people," Cooley said.
Noguez, whose office sets property tax rates on county residences and businesses, was elected in 2010 after a career as an appraiser for the county. County prosecutors began investigating allegedly improper tax breaks for wealthy property owners that began after Noguez took office, the Times reported.
The investigation looked into whether assessor's office workers were pressured to give property tax breaks to clients of Noguez campaign contributors, the newspaper said.
Investigators searched Noguez's home and 11 other locations in April after a former official accused the assessor of political corruption. Scott Schenter said Noguez pressured him to raise money for his election campaign in 2010.
Search warrants were issued for Noguez's downtown headquarters, satellite offices, two Internet service providers and the Phoenix home of businessman Ramin Salari, who contributed to Noguez's campaign. Salari, a friend of Noguez, had received large tax reductions for residential and commercial properties, the newspaper reported.
Schenter resigned in 2011 after his supervisor discovered he reduced the taxable value of 151 properties in the county without explanation or authorization, the Times said.
Noguez -- who has been on paid leave from his $192,000 post since June -- denies telling Schenter to lower anyone's taxes.