He warns that urgent reform is needed to prevent wealth concentration from harming democracy.
Newsom's proposal aligns him with the populist left as he considers a 2028 presidential run.
He proposes a minimum tax on those with over $100 million in net worth and wants to prevent the wealthy from borrowing against stock portfolios tax-free.
Newsom opposes a California measure taxing billionaires, arguing the issue should be addressed federally to prevent billionaires from leaving the state.
