Cal. Rev. & Tax. Code § 32103

Subject to the limitations provided in this article, the board shall fix the total amount of the security required of any taxpayer and may increase or reduce the amount at any time. In fixing the total amount, the board may set an amount which is not less than five hundred dollars ($500) and not more than twice the taxpayer’s estimated monthly tax for taxpayers reporting monthly, or not more than twice the taxpayer’s estimated tax for the tax reporting period for taxpayers reporting for periods longer than one month ascertained in any manner as the board may deem proper.