# Billionaire Tax Could Cost California $39 Billion

> Stanford economists warn Prop 40 billionaire tax might cost California $39 billion long-term.
- Title: Billionaire Tax Could Cost California $39 Billion | Shortify
- Summary: Stanford economists warn Prop 40 billionaire tax might cost California $39 billion long-term. Stanford economists say California could lose $39 billion from…
- Keywords: california, prop 40, billionaire tax, stanford university, hoover institution, billionaires, wealth tax, california state, tax revenue, billionaire wealth, news, local
- Source: Sfchronicle — https://sfchronicle.com/california/article/billionaire-tax-analysis-22485993.php
- Read time: 1 min
- Topics: california, prop 40, billionaire tax, stanford university, hoover institution, billionaires, wealth tax, california state, tax revenue, billionaire wealth, news, local
## Prop 40 on ballot
Californians vote on a proposed billionaire wealth tax as Proposition 40.
## Stanford economists report
Stanford University’s Hoover Institution economists say the tax would collect only $36 billion, not the $100 billion projected.
## Wealth tax revenue drop
The tax would lose $30 billion to $40 billion in income tax revenue from wealthy residents leaving California.
## Prop 40 details
Prop 40 would levy a one-time 5% wealth tax on people with at least $1 billion net worth living in California on Jan. 1, 2.026.
## Billionaires leaving
Some billionaires have already left California before the Jan. 1, 2026 deadline.
## Billionaire PAC funding
A billionaire-backed PAC has spent over $300 million to defeat Prop 40.
## Zuckerberg stays
Meta CEO Mark Zuckerberg agreed to stay in California after a stock deal.
## Long-term loss estimate
Stanford economists estimate a net loss of $39 billion if Prop 40 passes.
## Key takeaway

Stanford economists say California could lose $39 billion from a proposed billionaire tax due to wealthy residents leaving.