Voters in California will decide Proposition 42 in November 2026, a constitutional amendment that would bar new state taxes on personal property ownership—including retirement accounts, financial assets, business interests, and intellectual property—while restricting most retroactive taxes based on pre-enactment conduct or residency. The measure directly conflicts with Proposition 40, the competing billionaire wealth tax initiative, creating a head-to-head contest where the higher vote total prevails under state rules. Trader sentiment remains closely balanced around even odds because business and taxpayer organizations have mobilized substantial funding to highlight risks to savings and investment, while supporters of the wealth tax emphasize revenue needs and question the measure’s fiscal impact estimates. Recent qualification of both initiatives in June, paired with ongoing legal analyses of retroactivity and due-process challenges, continues to shape expectations ahead of the fall campaign.