TL;DR
Proponents of wealth taxes are shifting from theoretical proposals to highly aggressive statutory designs featuring backward-looking residency traps and presumptive valuation formulas. However, these designs are colliding with severe real-world revenue shortfalls, deep-seated state-level constitutional barriers, and the practical necessity of building tax-deferral escape valves to prevent the forced liquidation of private businesses.
Subnational Policy Design and the Flight Calculus
State and regional legislatures are drafting highly aggressive residency traps and presumptive valuation formulas to prevent capital flight, yet real-world implementations continue to yield massive revenue shortfalls.
"For non-publicly traded business entities, the initiative establishes a highly aggressive presumptive valuation formula: Presumed FMV = [(entity book value) + (7.5 x entity annual book profits)] x taxpayer's ownership %"
— California 2026 Initiative
(Source: Baker Botts)
"[the solidarity tax] collected only EUR 623 million—a dismal 40.3% of the projected target. This shortfall is widely attributed to rapid asset restructuring, tax avoidance, and wealthy individuals relocating."
— Spanish Solidarity Tax
(Source: Tax Foundation)
These dynamics illustrate that while legislative drafts can establish strict mathematical proxies to value illiquid assets, they cannot easily restrict the global mobility of the tax base. When the reality of wealth flight sets in, actual revenues frequently fall far short of the optimistic projections generated by academic models California 2026 Initiative.
What to watch: Watch whether California's Proposition 40 survives legal challenges to its backward-looking residency hook if it passes in November 2026 California 2026 Initiative.
Constitutional Boundaries and Judicial Overreach
The legal battle lines over taxing unrealized wealth are hardening as courts consistently restrict the definition of taxable income.
"For nearly a century, Washington courts have been clear: income is property, and property taxes must be uniform and limited..."
— Washington Constitutional Constraints
(Source: Citizen Action Defense Fund)
"...the Court's holding did not decide 'the constitutionality of a congressional tax on appreciation of property or net worth.'"
— Federal Wealth Tax Proposals
(Source: Moore v. United States)
These legal limits force wealth tax proponents into a difficult double-bind: they must either defend non-uniform taxes under restrictive state constitutions or risk having federal plans struck down by a Supreme Court that has signaled deep skepticism toward taxing unrealized gains Federal Wealth Tax Proposals. This legal fragility makes any projected revenue highly speculative, as courts remain the ultimate arbiters of what constitutes "income" Washington Constitutional Constraints.
What to watch: Watch how Klickitat County Superior Court rules on the constitutional challenge to Washington's newly enacted Millionaires' Tax Washington Constitutional Constraints.
The Liquidity Trap and Structural Redesigns
Even long-standing wealth tax regimes are being forced to build escape valves to prevent business owners from being forced to liquidate illiquid assets to pay their tax bills.
"...the government established a permanent deferral scheme. Taxpayers can defer their wealth tax payments for up to three years if their liability exceeds NOK 30,000. This is targeted at owners of listed/unlisted shares, commercial real estate, and operating assets."
— Norwegian Bø Experiment
(Source: Aider Legal)
This policy pivot demonstrates that the "liquidity trap"—where taxpayers hold massive paper wealth but lack the cash to pay annual levies—is a real operational barrier to wealth taxation Norwegian Bø Experiment. When governments do not build these mechanisms, they risk driving away their most productive business owners to more stable jurisdictions like Switzerland Norwegian Bø Experiment.
What to watch: Watch if other European nations adopt similar deferred payment structures to mitigate the economic harm of taxing illiquid private entities Norwegian Bø Experiment.
What surprised us
- The Massive Revenue Miss in Spain: Spain's much-touted solidarity tax on great fortunes brought in only 40.3% of its projected EUR 1.5 billion revenue target, showing how quickly wealthy taxpayers can restructure assets or relocate when faced with high effective tax rates Spanish Solidarity Tax.
- The Dutch Fictitious Return Disaster: The Dutch Supreme Court repeatedly struck down the country's wealth tax system in 2021 and June 2024 because it taxed citizens on "fictitious" returns rather than actual yields, forcing the government to pay out massive taxpayer compensation European Wealth Tax History.
- The Self-Defeating "Tax Haven" of Bø: The Norwegian municipality of Bø tried to lower its municipal wealth tax to 0.2% to attract billionaires, but Norway's national municipal tax equalization system clawed back the gains, leaving the town with a fiscal deficit that required emergency state support Norwegian Bø Experiment.
- Sanders-Khanna's Political Fallout: Representative Ro Khanna's endorsement of the federal 5% billionaire wealth tax bill in March 2026 triggered an immediate political backlash from his own Silicon Valley tech donors, exposing the sharp divide between progressive tax policy and the interests of tech-heavy constituencies Federal Wealth Tax Proposals.
Since last time
The wealth tax debate has pivoted from theoretical revenue modeling and administrative design to a focus on implementation failure, constitutional fragility, and the "liquidity trap."
- Escalated — Constitutional/Legal Risk: Previously a subset of the Washington state analysis, this is now a core pillar of the briefing. The focus has shifted from state-level repeal politics to the broader, existential legal threats posed by Moore and state-level judicial definitions of income.
- Demoted — California/State Policy: We have moved away from the "Missing Billionaire" math and Pareto tail extrapolation. California policy is now discussed primarily through the lens of "residency traps" and implementation challenges rather than revenue potential.
- Disappeared — The following items are no longer covered:
- The NBER/Saez/Zucman "Missing Billionaire" data and Pareto tail methodology.
- The specific Washington State repeal initiative (IP26-645) and its impact on social safety nets.
- The federal S. 4246 legislative details and IRS enforcement funding.
- All previous "What Surprised Us" bullets.
- Unchanged — None. The entire briefing has shifted focus to address new empirical failures and legal roadblocks.
Subnational Policy Design and the Flight Calculus (Demoted/Reframed)
While our previous update focused on the revenue potential of state-level taxes, the current discussion has shifted to the "flight calculus"—the reality that aggressive statutory designs often trigger capital flight and revenue shortfalls.
"For non-publicly traded business entities, the initiative establishes a highly aggressive presumptive valuation formula: Presumed FMV = [(entity book value) + (7.5 x entity annual book profits)] x taxpayer's ownership %"
— California 2026 Initiative (Source: Baker Botts)
"[the solidarity tax] collected only EUR 623 million—a dismal 40.3% of the projected target. This shortfall is widely attributed to rapid asset restructuring, tax avoidance, and wealthy individuals relocating."
— Spanish Solidarity Tax (Source: Tax Foundation)
The Delta: We are no longer debating the potential to capture revenue from "hidden" billionaires. The focus is now on the failure of these models to account for global mobility and asset restructuring.
Constitutional Boundaries and Judicial Overreach (Escalated)
The legal landscape has hardened. Where we previously looked at the administrative mechanics of federal proposals, we are now looking at the constitutional wall that proponents are hitting.
"For nearly a century, Washington courts have been clear: income is property, and property taxes must be uniform and limited..."
— Washington Constitutional Constraints (Source: Citizen Action Defense Fund)
"...the Court's holding did not decide 'the constitutionality of a congressional tax on appreciation of property or net worth.'"
— Federal Wealth Tax Proposals (Source: Moore v. United States)
The Delta: The legal fragility of these taxes is now the primary story. Proponents are caught in a double-bind: they must defend non-uniform taxes under state constitutions while facing a Supreme Court that has signaled deep skepticism toward taxing unrealized gains.
The Liquidity Trap and Structural Redesigns (New)
This section addresses a new operational reality not covered in the previous briefing: the "liquidity trap." Governments are finding that without "escape valves," wealth taxes force the liquidation of private businesses.
"...the government established a permanent deferral scheme. Taxpayers can defer their wealth tax payments for up to three years if their liability exceeds NOK 30,000. This is targeted at owners of listed/unlisted shares, commercial real estate, and operating assets."
— Norwegian Bø Experiment (Source: Aider Legal)
The Delta: This is an entirely new operational focus. We are moving from "how do we tax wealth" to "how do we prevent wealth taxes from destroying the underlying business."
What surprised us
- The Massive Revenue Miss in Spain: Spain's much-touted solidarity tax on great fortunes brought in only 40.3% of its projected EUR 1.5 billion revenue target, showing how quickly wealthy taxpayers can restructure assets or relocate when faced with high effective tax rates [NEW] Spanish Solidarity Tax.
- The Dutch Fictitious Return Disaster: The Dutch Supreme Court repeatedly struck down the country's wealth tax system in 2021 and June 2024 because it taxed citizens on "fictitious" returns rather than actual yields, forcing the government to pay out massive taxpayer compensation [NEW] European Wealth Tax History.
- The Self-Defeating "Tax Haven" of Bø: The Norwegian municipality of Bø tried to lower its municipal wealth tax to 0.2% to attract billionaires, but Norway's national municipal tax equalization system clawed back the gains, leaving the town with a fiscal deficit that required emergency state support [NEW] Norwegian Bø Experiment.
- Sanders-Khanna's Political Fallout: Representative Ro Khanna's endorsement of the federal 5% billionaire wealth tax bill in March 2026 triggered an immediate political backlash from his own Silicon Valley tech donors, exposing the sharp divide between progressive tax policy and the interests of tech-heavy constituencies [NEW] Federal Wealth Tax Proposals.
Open threads
- Washington State Repeal Initiative (IP26-645): The previous focus on this initiative has been absorbed into the broader discussion of constitutional challenges. The specific legislative battle is now secondary to the overarching judicial questions regarding "income as property."
- Federal S. 4246: The previous focus on the administrative machinery of this bill has been superseded by the broader, more urgent analysis of the Supreme Court's stance on unrealized gains post-Moore.