The proposed 2026 Billionaire Tax Act may result in a tax rate higher than 5% for some of California's most prominent billionaires due to a provision regarding voting control rights.

The tax calculation is based on the percentage of the business entity owned by the taxpayer, which is presumed to be not less than the taxpayer's percentage of overall voting or other direct control rights.

The effective tax rate for billionaires such as Sergey Brin, Larry Page, and Mark Zuckerberg could be significantly higher than 5% due to their voting control rights in companies like Alphabet and Meta.

bloomberg.com - A proposed billionaire tax exposes the dual share racket?

So the BRK A share owning billionaires in CA beware. A shares have 10,000 times the voting rights of the B shares, but only 1,500 times the economic rights.