Meta CEO Mark Zuckerberg has agreed to keep living in Silicon Valley for eight years, potentially exposing himself to billions of dollars in one-time taxes if California voters approve a contentious ballot measure next month, according to a company regulatory filing released Wednesday.

During a dinner with Meta board members on September 9, Zuckerberg informed them that he was considering leaving California because of the measure, known as Proposition 40, and that he planned to list his Palo Alto, California, home for sale four days later, the 109-page filing stated. The ballot proposal, which could be subject to lawsuits even if voters approve it, calls for a one-time 5 percent tax on stock and other assets held by billionaires in the state as of January 2026.

Many wealthy individuals, including Zuckerberg, currently avoid significant tax payments by borrowing against their shares and taking low salaries—$1 annually in the Meta CEO’s case. Zuckerberg purchased a home in Florida this past February, The Wall Street Journal reported at the time.

His potential cross-country move concerned a special committee of the board, whose members included attorney Robert Kimmitt, venture capitalist Charlie Songhurst, and DoorDash CEO Tony Xu. “The special 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,” according to Wednesday’s filing.

Within days of the Meta board dinner, the special committee and Zuckerberg reached an agreement that links his ability to sell special company shares to his continued residence in California. It was finalized a week ago, and on Wednesday, Meta announced the details. It plans to create a new class of shares that hold no voting power. Selling these shares could potentially help raise funds for Meta’s expensive investments in AI data centers, without diluting Zuckerberg’s existing voting control.

All existing shareholders will receive the new nonvoting shares automatically in proportion to their existing holdings. Under what Meta called a “Founder Alignment Agreement” with Zuckerberg, he can sell 20 percent of those new shares to help pay any taxes he may owe. The remaining 80 percent would be available for sale in chunks over the next eight years as long as he remains in California. Any attempt to sell them early would require offloading some of his voting shares “unless there are material unforeseen circumstances that would render it prudent or advisable for Zuckerberg to reside elsewhere.”

Notably, the agreement specifies that Zuckerberg merely has to remain wherever Meta maintains its headquarters, so it’s possible that both he and the company could move together to another state. A number of California companies have left for Texas, Nevada, and other states in recent years. Google cofounders Sergey Brin and Larry Page are among the handful of billionaires widely believed to have exited California over the potential tax.

But with much of the most pioneering AI development happening in Silicon Valley, leaving the city of Menlo Park could be a difficult proposition for the Meta board to stomach. “The goal is to keep Zuckerberg continuing to lead the company from California and in close proximity to Meta Superintelligence Labs,” the filing stated, referring to the company unit behind its recent Muse AI models.

In the end, the exercise may have been for naught. Recent polling in California suggests that with about $129 million spent campaigning against Prop 40, it will fail to muster enough votes.