California’s Proposed Billionaire Wealth Tax and the Question of State Residency

From the moment initial paperwork was filed in October 2025 to put the California Billionaire Tax Act (CBTA) on the ballot, public debates have focused on the question of exit: won’t billionaires simply pack up and move to a different state to avoid paying the tax? That question quickly ceased to be hypothetical. According to news reports in the months that followed, at least six billionaire executives, and possibly others, have taken steps to abandon their California residency prior to the measure’s effective date of January 1, 2026. A recent study from researchers at the Hoover Institution at Stanford estimated that these six individuals account for nearly 30% of the measure’s wealth tax base, suggesting that even lower-bound estimates of taxpayer exit could meaningfully undercut the measure’s revenue potential.[1] But these projections, as well as the rosier ones offered by the CBTA’s proponents, depend heavily on assumptions about how California law actually works in this area.

Can billionaires simply switch their state residency and avoid the tax? Most press accounts, as well as the Hoover study, treat the residency question as one that answers itself via self-certified acts: a billionaire announces a new home state, purchases property there, or moves a business entity, and the desired legal outcome automatically materializes. This framing radically oversimplifies the complex inquiry required to determine whether an individual has ceased to be a California resident as a matter of law. The measure’s proponents acknowledge this legal complexity, noting that California residency “looks to subjective and objective factors” and “is not a simple binary” as opponents claim. But they too seem to take the answer as straightforward, concluding that “the taxpayer’s residency is already largely set” and that “moving does not allow billionaires to avoid the tax.”[2]

Both framings, however different in aim, elide the true nature of California law, which involves a genuinely indeterminate, fact-intensive inquiry before any residency determination can be made. Not all areas of law are like this. Some legal status determinations turn on a simple triggering event that is objectively verifiable and legally sufficient to “switch” one’s status from X to Y – for example, whether one is married or not, convicted or not, old enough to vote or not, etc… But California residency law has no such switch. Instead, it has a thalweg.

Wait, what?

Bear with me. A thalweg (from the German Talweg, or “valley path”) is the line that connects the points of lowest elevation within a watercourse; in practical terms, it is the deepest thread of the channel through which a river flows. In international law, the Thalweg Principle is sometimes used to determine a boundary between two nation states. As the course of the river shifts over time through accretion or erosion, the boundary shifts with it, always tracking the deepest thread of the channel. The relevant point is that a physical fact (the location of the deepest thread) determines legal consequences, and as that fact changes, so do the entitlements that depend on it. California residency law works the same way: not a switch, but a deep line that must be found, and that can shift as the underlying facts of a person’s life evolve.

So what happens when a billionaire decides to move to another state? California law treats as a resident anyone who is in the state for other than a temporary or transitory purpose, as well as those who are domiciled in California but outside the state for a temporary or transitory purpose.[3] Thus, there is both a question of domicile and a question of whether one’s presence in a particular place is “temporary or transitory.” It is possible that those claiming to have already left will be deemed non-residents under these provisions. But this determination is not made by mere announcement, new home purchases, or ministerial acts such as changing the formal registration of one’s limited liability companies. Instead, the law requires asking how close one’s connections are with California as compared with other states, with an emphasis on how (and why) that comparison has shifted over time. This “closest connections” inquiry, which is stated most explicitly in administrative regulations, is meant to operationalize the “temporary or transitory purpose” language referenced above. Because these provisions have been incorporated by reference in the CBTA, they are likely to be central in resolving any disputes over attempted pre-2026 moves.

The State Board of Equalization’s 2003 Bragg decision, the leading authority on “closest connections,” identifies 19 relevant factors for making the determination.[4] Readers interested in reviewing the full list of Bragg factors can do so here or in the table reproduced at the end of this essay. In more recent rulings, the Office of Tax Appeals has divided these factors into three categories: (1) those relating to one’s physical presence and the location of real property, (2) those involving personal and professional associations, including the location of one’s spouse and children, and (3) various formal registrations and filings, such as one’s driver’s license and voter registration.[5] Just as important as the factors themselves is the common admonition that this list is not meant to be exhaustive and that no factor or factors should be regarded as determinative. One might imagine that alternative factors might be relevant to the billionaire class as compared to ordinary folk. Also, the idea is not to count the factors to see if more point to California versus some other state. Rather, the factors are “meant to serve as a guide,” a mere starting point in a “totality of the circumstances” evaluation of the entirety of a person’s life connections to place. Like a thalweg, what matters most is finding the connections with the greatest depth. Does the deepest thread run through California or somewhere else?

Beyond the substance of the closest-connection test, the framework also carries certain built-in presumptions that independently shape every exit case. California law treats prior domicile as legally persistent: once one’s domicile is established, it continues unless and until the taxpayer carries the burden of proving a new one. When evidence is uncertain or incomplete, as it often will be in cases involving complex, multi-state lives, this presumption resolves the doubt against the party asserting that domicile has changed. A similar presumption obtains as to residence: one attempting to disclaim California residency must demonstrate that their departure is not merely temporary. Absent that affirmative showing, California residency endures as a matter of law.[6] These two presumptions operate independently and must be overcome on separate legal grounds, even though there is often substantial overlap in making domicile and residence determinations. Thus, a complete exit requires defeating both presumptions: changed domicile and physical absence that is not merely temporary.

Introducing “Marcus Hale”

How might this framework apply to the six billionaires claiming to have terminated their residency prior to the CBTA effective date? With limited information about these individuals and the actions they have taken, a proper evaluation of the merits is not yet possible. Instead, I asked Claude (Anthropic’s AI program) to construct a hypothetical billionaire — “Marcus Hale”— whose life, circumstances, and 2025 actions represent a rough composite of what public reports have revealed about the actual six billionaires.

Marcus Hale, 54, has a net worth of roughly $180 billion, derived primarily from a co-founding stake in Arcspan, a cloud infrastructure company that went public in 2009. Hale stepped back from day-to-day operations in 2018 but retains a 7% economic stake and a board seat. His super-voting shares became legally significant in October 2025, when counsel identified that the initiative’s language could be read to value his stake at voting-control rather than economic weight, potentially tripling his nominal tax exposure. He manages his affairs through Meridian Coast Advisors LLC, an Atherton-based family office overseeing dozens of subsidiary LLCs.

A Midwest native with no childhood roots in California, Hale has lived in the state since 1995 — an entirely adult, entirely elective tenure. He received a master’s degree in computer science from UC Berkeley in 1997. His wife, Priya Nair, is an immunologist and UCSF faculty member currently on a two-year research leave, during which she has focused on a book manuscript and a European research collaboration, including six weeks at a Geneva institute. Her UCSF appointment remains formally active; she has not resigned, and her colleagues expect her return. The couple’s two children — Oliver (17, admitted early decision to an East Coast university, departing August 2026) and Leila (15, engaged in a geographically open college search) — remain enrolled in California schools. The family’s primary residence since 2011 is a $28 million home in Atherton, staffed and retained; a Carmel weekend property is also retained. Neither was listed for sale.

In the ten days before Christmas 2025, Meridian Coast Advisors and fourteen affiliated LLCs filed conversion documents with the California Secretary of State, reincorporating in Delaware and Nevada. Hale’s aviation holding company was converted to a Florida LLC with a Miami address. A Florida entity, Meridian Coast Florida LLC, had been formed quietly in March 2025 — nine months before the snapshot date, with purpose unclear. On December 11, Hale closed on a $58 million waterfront property in Miami’s Bay Point neighborhood; the Wall Street Journal reported he had been considering a Florida move since at least summer 2025. On December 28, he resigned from the board of a San Francisco arts institution but not from the Arcspan board. He did not change his voter registration. Priya took no action regarding her UCSF appointment. A person described as familiar with Hale’s plans confirmed to a financial outlet that he intended Miami to be his primary residence; his representatives did not comment. He spent December 29–31 at the Miami property and was back in the Bay Area by January 3.​​​​​​​​​​​​​​​​

The table below summarizes what we know about Hale’s announced departure from California.

How Might the Marcus Hale Case Be Decided?

Has Hale successfully terminated his California residency prior to January 1, 2026? To be sure, he has undertaken several specific substantive actions: fourteen LLC conversions, a $58 million Florida property purchase, a civic board resignation, a new Florida-registered aviation entity, and a Florida LLC formed nine months before the snapshot date. These are all documentable, concrete steps that support the position that he is no longer a California resident. But the inquiry would not stop there. Hale’s Atherton home remains fully staffed and available. His wife’s UCSF appointment is formally active, even if she is on leave. His children remain enrolled in California schools through the end of the 2025–26 academic year, even though Oliver’s departure is imminent and Leila’s future is genuinely open. His voter registration is unchanged. He spent three days in Miami over New Year’s and returned to California almost immediately.

Critically, the evidentiary picture will not be frozen at January 1, 2026. Subsequent conduct can also be relevant in determining the precise moment in time when someone has ceased being a California resident. For example, if Hale’s spouse returns to UCSF in 2027, as her colleagues expect, that fact will be available as circumstantial evidence that her 2025 leave was always intended as temporary, and by extension that the family’s center of gravity never genuinely shifted. Similarly, if Hale spends the majority of 2026 in the Bay Area, attending Arcspan board meetings, managing his philanthropic portfolio, and being present for Leila’s high school life; those facts too will be weighed in the determination.

What Hale’s case illustrates is not that he did nothing, but that what he did was partial and asymmetric: his business restructuring was aggressive and well-documented, while his personal life remained suspended in genuine ambiguity rather than definitively resolved in favor of Florida. Whether that ambiguity helps or hurts him depends on events over the next two to three years, well after the snapshot date has passed. Hale’s most distinctive legal feature is the combination of a spouse whose California professional ties are suspended but not severed, and children who are on the verge of leaving California independently, a fact pattern that the FTB could frame as a temporary life-stage transition rather than genuine relocation.​​​​​​​​​​​​​​​​

Published appellate decisions in California residency disputes are remarkably scarce; the overwhelming majority of contested cases are resolved at the level of the State Board of Equalization or, today, the Office of Tax Appeals. The few decisions that have reached the courts of appeal therefore carry particular weight. Noble v. Franchise Tax Board is one such decision, and it is directly relevant to the CBTA’s snapshot-date problem.[7] The case did not turn on whether the taxpayers had ultimately abandoned California residency; the court accepted that they had. The question was whether their departure had taken legal effect by the specific dates on which taxable transactions occurred. That framing maps closely onto the CBTA’s structure, which imposes liability based on residency as of a single date rather than over a period. If Noble is any guide, the FTB could argue, and a state court of appeal might well agree, that a taxpayer’s conduct did result in a genuine termination of California residency, but that the totality of the circumstances places the operative date of that change some time after January 1, 2026.

Checking Out of Hotel California

The most common “joke” one hears about California residency law – ok, maybe the only joke –usually involves some reference to the iconic closing line from the Eagles 1976 hit, Hotel California: “You can check out any time you like, but you can never leave!” It’s meant as a wry dig at the state’s tax enforcement efforts through aggressive residency audits. But the joke lands (if it lands at all) for two different reasons. There’s the “it’s funny because it’s true” explanation that no doubt resonates for many, particularly those with the lived experience of undergoing an FTB residency audit. But another common source of humor is incongruity; in this case, the absurdity of framing a fundamental uprooting of one’s life, leaving one community and joining another, as akin to checking out of a hotel. Not “it’s funny because it’s true” but just the opposite: “it’s funny because it’s false.” We all know that a family’s decision to move is more meaningful, more momentous, than a final night at the Hampton Inn.

As the preceding analysis has shown, California law treats a change of residence not as an act of consumer choice, not checking out of one hotel and into another, but as something closer to an act of hydrological engineering. In 1900, the City of Chicago reversed the flow of the Chicago River, redirecting it away from Lake Michigan and into the Illinois and Michigan Canal to protect the city’s drinking water. It is now widely cited as one of the great engineering feats of the early twentieth century. But the reversal didn’t happen because engineers declared the river to flow in a new direction. Shifting the river’s thalweg required twenty-eight million pounds of dynamite, years of labor, and the construction of an entirely new channel capable of sustaining the river’s altered course. California residency law works, in its own way, on the same principle. The law asks where the deepest, most persistent currents of a person’s life are flowing. It asks where their family lives, where their doctors practice, where their professional relationships are rooted, where they think of when they think of home. A taxpayer who wants to redirect those currents must actually redirect them, establishing connections in the new state that surpass those left behind. Filing new paperwork and changing an address is no more effective than posting a sign at the riverbank.

The practical consequence of this complexity is that neither side’s revenue projections can be taken at face value, because both depend on residency determinations that the applicable legal framework leaves irreducibly open. Whether any particular individual was a California resident on January 1, 2026 is a question that will be answered, if it is answered at all, years later, through litigation whose outcome is genuinely uncertain. The six individuals whose departure claims most directly bear on the measure’s projected yield may win some of those cases, lose others, and settle still others on terms that produce a fraction of the tax nominally owed. California’s residency law, properly understood, does not guarantee that the state can hold the door closed. It guarantees only that the question of exit will be decided on substance, not form. No one, on either side of this debate, can know where the deepest currents were running until the adjudication is done.

California’s “Closest Connections” Analysis: The Bragg Factors

Appeal of Stephen D. Bragg, 2003-SBE-002 (Cal. State Bd. of Equalization, May 28, 2003)

Three-category framework per Appeal of L. Mazer & M. Mazer, 2020-OTA-263P; Appeal of D. Beckwith, 2022-OTA-332P

Factors “serve merely as a guide”; list is “not exhaustive”; the test is totality of circumstances, not whether a majority of factors is satisfied.

[1] Benjamin Jaros, Joshua D. Rauh, Gregory Kearney, John Doran, Matheus Cosso, The Net Present Value of the Billionaire Tax Act: An Assessment of the Fiscal Effects of California’s Proposed Wealth Tax (March 2026) (available at https://www.hoover.org/research/net-present-value-billionaire-tax-act-assessment-fiscal-effects-californias-proposed).

[2] Brian Galle, David Gamage, Emmanuel Saez, Darien Shanske, Expert Report On The California 2026 Billionaire Tax: Revenue, Economic, and Constitutional Analysis (December 31, 2025) (available at https://eml.berkeley.edu/~saez/galle-gamage-saez-shanskeCAbillionairetaxDec25.pdf).

[3] California Revenue and Taxation Code, Section 17014.

[4] Appeal of Stephen D. Bragg, Cal. St. Bd. of Equal., No. 2003-SBE-002 (May 28, 2003).

[5] See Appeal of L. Mazer and M. Mazer, Cal. Office of Tax Appeals, No. 2020-OTA-263P (2020); Appeal of Beckwith, Cal. Office of Tax Appeals, No. 2022-OTA-332P (2022).

[6] RTC 17014(c).

[7] Noble v. Franchise Tax Board, 118 Cal.App.4th 560 (Cal. Ct. App., 2d Dist. 2004).