California Proposition 42 would amend the state constitution to bar new taxes after January 1, 2026, on ownership or control of personal property such as retirement accounts, financial assets, business interests, and intellectual property, while also limiting most retroactive taxes based on prior conduct or residency status, with narrow emergency exceptions. The measure sits on the November 3, 2026, ballot alongside Proposition 40, a competing wealth-tax initiative that applies retroactively to billionaires’ assets as of January 1, 2026; under California’s conflict rule, the measure receiving more votes would prevail. Trader consensus remains near even because organized taxpayer groups back the protections for savings and planning certainty, while revenue-focused interests and proponents of the wealth tax highlight potential future revenue losses and question the scope of the retroactivity limits. Key variables that could shift the balance include relative campaign spending, polling trends on both measures, voter turnout patterns, and any pre-election legal challenges testing retroactive tax provisions.