**Proposition 43 would require a two-thirds voter approval threshold for citizen-initiated local special taxes starting January 1, 2027, closing the Upland loophole that currently allows such measures to pass by simple majority.** This legislatively referred constitutional amendment emerged from a June 2026 compromise that withdrew a broader Howard Jarvis Taxpayers Association initiative, avoiding retroactive invalidation of existing taxes like Los Angeles’ Measure ULA while narrowing the scope to prospective changes on initiative-driven special taxes. Supporters highlight taxpayer protections and consistency with Proposition 13 supermajority rules for government-proposed taxes. Opponents emphasize risks to local revenue for services such as schools, housing, and emergency response, arguing it constrains voter-approved funding options. The closely balanced market odds reflect uncertainty over November turnout, campaign spending by business and labor groups, and voter preferences on local tax flexibility versus fiscal restraint, with no major new developments since the compromise. Outcomes could shift with endorsements, advertising intensity, or polling trends on similar revenue measures.