A version of this article first appeared in CNBC’s Inside Wealth newsletter with Robert Frank, a weekly guide to the high-net-worth investor and consumer. Sign up to receive future editions, straight to your inbox.The proposed California billionaire tax includes a special provision that makes it highly unlikely that anyone who wants to leave the state could avoid paying, according to tax attorneys.The Billionaire Tax Act, which could be added to the state’s general election ballot in November, would impose a one-time tax of 5% on the total wealth of California tax residents whose net worth is $1 billion or more. While new taxes typically take effect after they’re approved, the proposed billionaire tax would apply to those who are California residents as of Jan. 1, 2026. The retroactive date left little time for California’s estimated 200 to 250 billionaires to change their tax residency after they first learned of the potential tax in December.”The reason they did this is obvious,” said Christopher Manes of Manes Law. “If they had made the date in November, after passage, you’d have 200 people who could get out in time and save millions of dollars.”California tech billionaire Peter Thiel announced last week that he had “established a significant presence in Miami over the last several years, maintaining a personal residence in the city since 2020” and an office for his Founders Fund venture capital firm since 2021. Attorneys told CNBC that at least two other unnamed California billionaires have moved or made plans to move since the end of last year.Nvidia CEO and California billionaire Jensen Huang, however, told Bloomberg he is “perfectly fine” with the proposed tax. Get Inside Wealth directly to your inboxThe Inside Wealth newsletter by Robert Frank is your weekly …