A measure to impose a one-time 5% tax on California billionaires could be on the ballot in November. Proponents say that the roughly $100 billion raised by the bill, which would tax about 200 people, would help offset federal cuts to health care. In an effort by lawmakers to prevent billionaires from fleeing California before the bill is passed, the tax would be retroactive to Jan. 1, 2026. CNBC’s Robert Frank breaks it down.