California’s Billionaire Tax Proposal Sparks Exodus Debate as IRS Data Shows Major Taxpayer Flight

California’s proposed wealth tax on billionaires has ignited fierce debate as new Internal Revenue Service data documents a substantial exodus of affluent taxpayers from the state. The measure, backed by the Service Employees International Union, would impose a one-time 5% tax on residents with net worth exceeding $1 billion and appears on the November ballot, applying retroactively to those who were state residents on January 1, 2026.

According to federal tax return data, Los Angeles County experienced the steepest decline, with 17,496 net tax filer departures taking approximately $1.9 billion in income elsewhere. Orange County lost 11,618 taxpayers, while San Diego, Riverside and San Bernardino counties each recorded losses exceeding 8,400 filers, demonstrating widespread migration from California’s largest population centers.

Billionaire investor Mark Cuban has emerged as a prominent critic, warning that the tax threatens to push not just wealthy individuals but investment capital and startup operations out of California. In recent comments directed at Democratic Representative Ro Khanna, an ardent tax supporter, Cuban stated he would relocate his residency and redirect major startup investments away from the state if the measure passes.

Proponents argue the tax would generate billions for healthcare and education initiatives, while opponents contend it accelerates wealth migration that ultimately undermines state and local funding for schools, public safety and infrastructure.