California voters will decide Proposition 42 on November 3, 2026, a constitutional amendment that would bar new state taxes after January 1 on personal assets such as retirement holdings and investments while restricting retroactive levies tied to prior residency or conduct. Trader sentiment sits near even because the measure directly offsets the competing wealth-tax initiative (Proposition 40) targeting billionaires, prompting substantial early fundraising from business-backed opponents and signature drives by proponents. Recent developments include qualification for the ballot after June signature deadlines and federal legislation introduced by Rep. Kevin Kiley to block retroactive state taxation of former residents. Outcomes hinge on relative campaign spending, turnout among high-asset voters versus revenue-focused groups, and any court rulings on the related wealth-tax measure's constitutionality before Election Day.