Californians Adapting to New Property Tax Rules In many states, calculating property taxes is pretty straightforward: It's a simple equation of your assessed property value and established tax rate. But in California, property taxes are far more complex. Numerous laws have been enacted in recent decades that mandate property tax rules in the Golden State. The most recent – Proposition 19, a statewide ballot measure passed by voters in November 2020 – went into effect Feb. 16, 2021. “Prop. 19 changes several tax rules, but the biggest impact will be on high-net-worth families ...