California Code, Revenue and Taxation Code - RTC § 24321

Notwithstanding any statute, ordinance, regulation, rule or decision to the contrary, no city, county, city and county, governmental subdivision, district, public and quasi-public corporation, municipal corporation, whether incorporated or not or whether chartered or not, shall levy or collect or cause to be levied or collected any tax upon income which is excludable from gross income and exempt from state taxes pursuant to Section 24320.

This section shall not be construed to authorize any such entity to levy a tax on, according to, or measured by, income or profits paid or accrued.