How Billionaires Are Fighting the Prop 40 California Wealth Tax

Every Tuesday for the last few months, two dozen of the world’s richest people or their advisers hop onto a conference call and plan for war.

The war is against a proposed tax, but not just any tax. It is against a “wealth tax” on California billionaires, one that Silicon Valley’s most affluent see as an existential threat that could usher in a new way of attacking them. So in confidential memos, WhatsApp and Signal chats and conference calls, they are banding together to battle back.

The calls are organized by Building a Better California, a nonprofit started this year to fight Proposition 40, the ballot measure that would impose a one-time 5 percent tax on billionaires if voters approve it next week. Each week, the nonprofit’s operatives brief donors or their advisers on polling, advertising and opposition research. Often, the calls include an ask: Would you consider giving a little more?

Eighty or so donors have provided more than $333 million to Building a Better California, state records show, making it among the best-funded political efforts in California history. The donor list is a who’s who of tech celebrities: the Google co-founder Sergey Brin; the former Google chief executive Eric Schmidt; the Stripe chief executive Patrick Collison; the legendary investor John Doerr.

“The effort to beat it is nothing short of an Avenger-level effort,” said Trevor Traina, a Silicon Valley investor who knows many of the billionaires socially but is not involved with the group. “Like the Avengers, this is not a homogenous group of people, but rather heroes of different stripes who share the same goal of protecting California. I, for one, pray they prevail.”