Meta CEO Mark Zuckerberg has agreed to keep living in Silicon Valley for eight years, a commitment that could leave him exposed to billions of dollars in one-time taxes if California voters approve a contentious ballot measure next month. The arrangement was disclosed in a 109-page company regulatory filing released Wednesday.

According to the filing, Zuckerberg told Meta board members at a September 9 dinner that he was considering leaving California because of the measure, known as Proposition 40. He said he planned to list his Palo Alto home for sale four days later. The proposal, which could face legal challenges even if voters pass it, would impose a one-time 5 percent tax on stock and other assets held by billionaires in the state as of January 2026.

Many wealthy people, Zuckerberg among them, currently limit their tax payments by borrowing against their shares and drawing small salaries. His salary as Meta's chief executive is $1 a year. The Wall Street Journal reported in February that he had bought a home in Florida.

The prospect of a cross-country move alarmed a special board committee that included attorney Robert Kimmitt, venture capitalist Charlie Songhurst and DoorDash CEO Tony Xu. The filing said the committee "was mindful about the difficulties the company faced during the COVID-19 pandemic when Zuckerberg could not be physically present with the company's management team and did not want the company to face similar challenges going forward."

Within days of the dinner, the committee and Zuckerberg reached a deal that links his ability to sell certain special company shares to his continued California residency. The agreement was finalized a week ago, and Meta announced its details on Wednesday. The company plans to create a new class of nonvoting shares, the sale of which could help fund its costly AI data center investments without diluting Zuckerberg's existing voting control.

All current shareholders will automatically receive the new shares in proportion to their holdings. Under what Meta calls a "Founder Alignment Agreement," Zuckerberg may sell 20 percent of his new shares to help cover any taxes he owes. The other 80 percent can be sold in portions over the next eight years, provided he stays in California. Selling them earlier would require him to offload some voting shares, "unless there are material unforeseen circumstances that would render it prudent or advisable for Zuckerberg to reside elsewhere."

The agreement requires only that Zuckerberg live wherever Meta has its headquarters, so he and the company could in theory relocate together to another state. Several California companies have moved to Texas, Nevada and elsewhere in recent years, and Google cofounders Sergey Brin and Larry Page are among a handful of billionaires widely believed to have left the state over the potential tax.

Still, with much of the most pioneering AI work taking place in Silicon Valley, abandoning Menlo Park could be hard for Meta's board to accept. "The goal is to keep Zuckerberg continuing to lead the company from California and in close proximity to Meta Superintelligence Labs," the filing said, referring to the unit behind the company's recent Muse AI models.

The effort may ultimately prove unnecessary. Recent polling in California suggests Proposition 40 will not gather enough votes, with about $129 million spent on campaigning against it.