Writing in Forbes, economist Teresa Ghilarducci examines the measures on California's 3 November ballot that could prevent the proposed billionaire tax from taking effect. Proposition 40 would impose a one-time tax of up to 5% on the wealth of billionaires who were California residents on 1 January 2026, with most of the revenue going to health care. Proposition 42 would add a constitutional bar on new state taxes on financial assets and other personal property, and Proposition 41 would restrict taxes exempt from the state spending limit. The official voter guide warns that if they receive more votes, they could stop Proposition 40 from becoming law. Ghilarducci, who supports Proposition 40, argues that the rival measures are being presented misleadingly as retirement protections.

The column notes that Governor Gavin Newsom endorsed Proposition 42 on 9 October, and that the committee behind Propositions 41 and 42 counts Sergey Brin and L. John Doerr III as its top donors. A recent Manhattan Institute poll found 50% of likely voters opposed to Proposition 40 and 35% in favour.

Why it matters: The vote is the most significant test so far of a state-level wealth tax in the US, and its use of a past residency date has already influenced where some billionaires live. Whatever the outcome, families with Californian ties are likely to face continued legal challenge and uncertainty over valuation and residence.

Source: Forbes, October 12, 2026. Wealth Office summarises reporting by other publications and links to the original.