TL;DR
The empirical question just got its best evidence yet — and it landed three weeks before California's Proposition 40 vote, the first-ever popular vote on a wealth tax. An NBER study of Norway's reform finds flight was real but cost only ~3.5 points of a 75% revenue gain, directly undercutting the Hoover Institution's claim that Prop 40 would produce a net fiscal loss. Meanwhile Hungary's tax went from rumor to statute-design with its own revenue haircut, and the 2028 Democratic primary has produced two competing federal designs.
California: the first popular vote on a wealth tax, with the administrability problem on full display
Proposition 40 is fighting a three-front war — counter-measures, money, and the Franchise Tax Board's capacity — and even its supporters concede the third front.
"If I were still controller, I'd have the Franchise Tax Board in a war room right now trying to figure this out."
— Politico
The FTB "doesn't appraise property" and would need to build, within six months, a system to value everything from stock to "art collections, wine vaults, cars" while auditing uncooperative centibillionaires — the Hyatt residency litigation lasted a quarter-century and reached the Supreme Court three times state-level-wealth-tax-proposals-california-2026-initiative
+2. The politics are equally tangled: Gov. Newsom endorsed Prop 42, the Brin-funded counter-measure that would permanently ban state wealth taxation, and under California's conflicting-initiative rule Prop 40 can "pass" and still die. Opposition spending tops $205 million; prediction markets give Prop 40 only ~30% despite PPIC polling at 52%.
The revenue claims are mirror-image elasticity bets. Hoover's study envisions "an 'Atlas Shrugged' scenario" producing "$25 billion in lost tax revenue," while proponents claim $100 billion — and Joel Slemrod notes the European repeals are "not immediately applicable" because those taxes "differed significantly in design," meaning neither estimate has a true precedent (LAist).
What to watch: The Nov 3 vote, and if Prop 40 passes, the first constitutional challenge — the Hoover paper predicts Due Process, Commerce Clause, Takings, and Bill of Attainder claims against its worldwide-wealth, retroactive-residency design.
Norway: the flight argument just got a number, and it's smaller than the narrative implied
The strongest peer-track evidence on wealth-tax feasibility landed this month, and it quantifies the thing everyone was arguing past.
"I estimate that absent any outmigration, wealth tax revenues would have increased by 75% from 2021 to 2024. Reform-driven outmigration lowers the revenue gain to 71.5%."
— NBER w35854
Marius Ring's study of Norway's 2021–2025 reform finds migration responses "concentrated among the top 0.1% of the wealth distribution" — at most 100 individuals — with no effects on startup founders, inventors, or firm investment norwegian-municipal-wealth-tax-bo-experiment-and-swiss-evidence
. This is direct ammunition against Hoover's -$25B California scenario, but with honest caveats: Norway's tax was an annual ~1.1% levy with full wealth registers, not a one-time 5% levy, and the short-run window can't rule out longer-run firm-location effects.
What to watch: Whether the Ring result survives contact with a 5% rate and a subnational tax in a federation full of zero-wealth-tax alternatives — which the California vote will now speak to.
Washington: the ballot-language effect is the story
Washington's I-645 repeal vote produced a small natural experiment in fiscal-impact disclosure, and the disclosure is winning.
"35% supported repeal, 57% opposed it and 8% were undecided"
— Seattle Times
That 22-point gap opens when voters see the legally required language warning repeal "would decrease funding" for schools and healthcare — a 13-point swing on a single sentence (MyNorthwest). The dueling revenue scores persist: the pro-tax coalition claims ~$3.5B/year from 20,000 households (Guardian), versus the prior DOR figure of ~$3.1B — check which base and year each uses. Underneath the vote, five of nine Supreme Court seats including Chief Justice Stephens are on the same ballot, and the Culliton v. Chase challenge waits washington-state-wealth-tax-study-and-constitutional-constraints
+1.
What to watch: The Nov 3 triple — repeal vote, court seats, and whether the slippery-slope expansion talk among some Democrats materializes into a bill.
Europe: Hungary publishes, Sweden debates reinstalling what it deleted, and the UK exodus gets contested
Hungary's tax went from party promise to formal proposal, and the revenue claim took a haircut before passing parliament. The Tisza government now "expects to generate 800 billion forints in revenue from this in four years" — roughly 200B/year, at the bottom or below Magyar's original 300–600B/year range (Ground News). The design is a mass-affluent tax — 1% above HUF 1 billion (~$3.08M), 1.5% above HUF 100B, real estate and foreign assets in the base — with first declarations due August 31, 2027, and still no published valuation methodology hungary-wealth-tax-proposal-2026-and-european-reversal-wave
.
Sweden's reinstatement debate exposed the reverse administrability lesson: "Sweden no longer maintains a complete tax register of wealth since the tax disappeared in 2007," so the Green Party's own 50-billion-crowns/year claim rests on estimates made without the register the repeal eliminated (Demócrata). The UK's £121B billionaire-exodus headline got a base-rate rebuttal from CenTax's Arun Advani: "a couple of highly reported examples don't in themselves indicate anything has changed" (Guardian) — and the UK changed its income-tax base for foreign residents, not a wealth tax.
What to watch: Hungary's August 31, 2027 first-declaration deadline — the hard checkpoint on whether a lower-capacity state can collect near its score.
The federal question: two designs, two feasibility logics
The 2028 primary has produced competing federal designs, and their structure reveals the actual feasibility arguments.
"You may not be able to pick up and move to Texas or Florida to shelter your income from taxation, but I promise you that billionaires can, and do… Wealth is movable, and it shops for the state with the lowest taxes."
— ABC News
Newsom opposes the state wealth tax while proposing a federal minimum tax on $100M+ net worth — the mobility and constitutional arguments both point federal. The Sanders–Khanna bill claims $400B/year from a 5% billionaire levy, which implies a ~$8 trillion base taxed with zero flight, avoidance, or valuation discount federal-wealth-tax-proposals-and-constitutional-impact-of-moore
— the same no-elasticity assumption the Norway paper just dented. Moore v. United States left several justices signaling a federal wealth tax would be unconstitutional under apportionment, though escape routes exist via inheritance taxation or framing unrealized gains as income.
What to watch: Prop 40's result as the trigger for the 2028 "raise-your-hand moment" — and whether any candidate's revenue claim survives contact with an elasticity assumption.
What surprised us
- The flight number is smaller than the story. The "exodus of Norwegian billionaires" narrative was never wrong — but it cost under 5% of the revenue gain, with zero detectable effect on founders, inventors, or firm investment norwegian-municipal-wealth-tax-bo-experiment-and-swiss-evidence. The strongest anti-tax argument just lost its quantitative edge.
- Repeal destroys the data needed to re-enact. Sweden's Green Party can't score its own proposal because the 2007 repeal eliminated the wealth register — an administrability argument nobody in the US debate is making european-wealth-tax-history-and-design-lessons
.
- Hungary discounted its own revenue before the vote. The implicit flight/avoidance haircut arrived pre-enactment with no published methodology — a rare case of a government self-flagging a contestable assumption.
- The ballot-language effect dwarfs the campaigns. A single legally mandated fiscal-impact sentence moved Washington opinion by 13 points — more than any ad war washington-state-wealth-tax-study-and-constitutional-constraints+1.
Open threads worth a vote
- [watch] Hungary parliament enacts (or stalls) the wealth tax before its Jan 1, 2027 start — does the bill pass with the announced design, and does an official fiscal score appear? Threads
- [watch] If Prop 40 passes: first constitutional challenge filing and FTB implementation steps. Threads
- [question] Adjudicate the Prop 40 revenue models: Hoover's -$25B vs proponents' +$100B, against NBER Norway evidence. Threads
Since last time
Entirely new this cycle: California's Prop 40 (the first popular vote on a wealth tax), the NBER Norway study quantifying flight, and a federal-designs section for the 2028 primary. None of these appeared in the previous briefing.
Promoted — California went from a passing reference ("the migration critique that defined the California story") to the lead section: Prop 40's three-front war and the FTB administrability problem.
Escalated — Two items grew in importance:
- Washington's ballot-language effect. Last time it was one polling detail (DHM's 57%/44% swing); now it's the headline finding of the section, with fresh poll numbers showing a 13-point move from a single mandated sentence.
- Hungary. Last time the bill was unpublished and the revenue claim failed visible arithmetic; now it's a formal proposal that self-haircut its own revenue estimate before enactment.
Demoted — Washington's court-election angle. Last time it was a full section plus the sole open thread; now it's a two-line mention at the bottom of the Washington section (five of nine seats including Chief Justice Stephens still on the Nov 3 ballot, Culliton v. Chase still waiting).
Disappeared — The Massachusetts Fair Share record is gone entirely. Last cycle's lead finding — three years of 2–3x collections and IRS data showing falling high-income outmigration — appears nowhere in this briefing. The "what to watch" (2024–25 IRS filings confirming or breaking the no-flight result) also went unaddressed. If you're tracking that thread, nothing here updates it.
Unchanged — No section is a pure carryover. The closest: Washington's DOR score (~$3.1B first-year) persists, now joined by a competing pro-coalition claim of ~$3.5B/year — see the Washington section for how to read the gap.
California: the first popular vote on a wealth tax, with the administrability problem on full display (Promoted)
Proposition 40 is fighting a three-front war — counter-measures, money, and the Franchise Tax Board's capacity — and even its supporters concede the third front.
"If I were still controller, I'd have the Franchise Tax Board in a war room right now trying to figure this out."
— Politico
The FTB "doesn't appraise property" and would need to build, within six months, a system to value everything from stock to "art collections, wine vaults, cars" while auditing uncooperative centibillionaires — the Hyatt residency litigation lasted a quarter-century and reached the Supreme Court three times state-level-wealth-tax-proposals-california-2026-initiative+2. The politics are equally tangled: Gov. Newsom endorsed Prop 42, the Brin-funded counter-measure that would permanently ban state wealth taxation, and under California's conflicting-initiative rule Prop 40 can "pass" and still die. Opposition spending tops $205 million; prediction markets give Prop 40 only ~30% despite PPIC polling at 52%.
The revenue claims are mirror-image elasticity bets. Hoover's study envisions "an 'Atlas Shrugged' scenario" producing "$25 billion in lost tax revenue," while proponents claim $100 billion — and Joel Slemrod notes the European repeals are "not immediately applicable" because those taxes "differed significantly in design," meaning neither estimate has a true precedent (LAist).
What to watch: The Nov 3 vote, and if Prop 40 passes, the first constitutional challenge — the Hoover paper predicts Due Process, Commerce Clause, Takings, and Bill of Attainder claims against its worldwide-wealth, retroactive-residency design.
Norway: the flight argument just got a number, and it's smaller than the narrative implied (New)
The strongest peer-track evidence on wealth-tax feasibility landed this month, and it quantifies the thing everyone was arguing past.
"I estimate that absent any outmigration, wealth tax revenues would have increased by 75% from 2021 to 2024. Reform-driven outmigration lowers the revenue gain to 71.5%."
— NBER w35854
Marius Ring's study of Norway's 2021–2025 reform finds migration responses "concentrated among the top 0.1% of the wealth distribution" — at most 100 individuals — with no effects on startup founders, inventors, or firm investment norwegian-municipal-wealth-tax-bo-experiment-and-swiss-evidence. This is direct ammunition against Hoover's -$25B California scenario, but with honest caveats: Norway's tax was an annual ~1.1% levy with full wealth registers, not a one-time 5% levy, and the short-run window can't rule out longer-run firm-location effects.
What to watch: Whether the Ring result survives contact with a 5% rate and a subnational tax in a federation full of zero-wealth-tax alternatives — which the California vote will now speak to.
Washington: the ballot-language effect is the story (Escalated)
Washington's I-645 repeal vote produced a small natural experiment in fiscal-impact disclosure, and the disclosure is winning.
"35% supported repeal, 57% opposed it and 8% were undecided"
— Seattle Times
That 22-point gap opens when voters see the legally required language warning repeal "would decrease funding" for schools and healthcare — a 13-point swing on a single sentence (MyNorthwest). The dueling revenue scores persist: the pro-tax coalition claims ~$3.5B/year from 20,000 households (Guardian), versus the prior DOR figure of ~$3.1B — check which base and year each uses. Underneath the vote, five of nine Supreme Court seats including Chief Justice Stephens are on the same ballot, and the Culliton v. Chase challenge waits washington-state-wealth-tax-study-and-constitutional-constraints+1.
What to watch: The Nov 3 triple — repeal vote, court seats, and whether the slippery-slope expansion talk among some Democrats materializes into a bill.
Europe: Hungary publishes, Sweden debates reinstalling what it deleted, and the UK exodus gets contested (Escalated — Hungary; Sweden and UK are new)
Hungary's tax went from party promise to formal proposal, and the revenue claim took a haircut before passing parliament. The Tisza government now "expects to generate 800 billion forints in revenue from this in four years" — roughly 200B/year, at the bottom or below Magyar's original 300–600B/year range (Ground News). The design is a mass-affluent tax — 1% above HUF 1 billion (~$3.08M), 1.5% above HUF 100B, real estate and foreign assets in the base — with first declarations due August 31, 2027, and still no published valuation methodology hungary-wealth-tax-proposal-2026-and-european-reversal-wave.
Sweden's reinstatement debate exposed the reverse administrability lesson: "Sweden no longer maintains a complete tax register of wealth since the tax disappeared in 2007," so the Green Party's own 50-billion-crowns/year claim rests on estimates made without the register the repeal eliminated (Demócrata). The UK's £121B billionaire-exodus headline got a base-rate rebuttal from CenTax's Arun Advani: "a couple of highly reported examples don't in themselves indicate anything has changed" (Guardian) — and the UK changed its income-tax base for foreign residents, not a wealth tax.
What to watch: Hungary's August 31, 2027 first-declaration deadline — the hard checkpoint on whether a lower-capacity state can collect near its score.
The federal question: two designs, two feasibility logics (New)
The 2028 primary has produced competing federal designs, and their structure reveals the actual feasibility arguments.
"You may not be able to pick up and move to Texas or Florida to shelter your income from taxation, but I promise you that billionaires can, and do… Wealth is movable, and it shops for the state with the lowest taxes."
— ABC News
Newsom opposes the state wealth tax while proposing a federal minimum tax on $100M+ net worth — the mobility and constitutional arguments both point federal. The Sanders–Khanna bill claims $400B/year from a 5% billionaire levy, which implies a ~$8 trillion base taxed with zero flight, avoidance, or valuation discount federal-wealth-tax-proposals-and-constitutional-impact-of-moore — the same no-elasticity assumption the Norway paper just dented. Moore v. United States left several justices signaling a federal wealth tax would be unconstitutional under apportionment, though escape routes exist via inheritance taxation or framing unrealized gains as income.
What to watch: Prop 40's result as the trigger for the 2028 "raise-your-hand moment" — and whether any candidate's revenue claim survives contact with an elasticity assumption.
What surprised us
- The flight number is smaller than the story. [NEW] The "exodus of Norwegian billionaires" narrative was never wrong — but it cost under 5% of the revenue gain, with zero detectable effect on founders, inventors, or firm investment norwegian-municipal-wealth-tax-bo-experiment-and-swiss-evidence. The strongest anti-tax argument just lost its quantitative edge.
- Repeal destroys the data needed to re-enact. [NEW] Sweden's Green Party can't score its own proposal because the 2007 repeal eliminated the wealth register — an administrability argument nobody in the US debate is making european-wealth-tax-history-and-design-lessons.
- Hungary discounted its own revenue before the vote. [UPDATED — sharpens last cycle's "fails the sniff test" finding] The implicit flight/avoidance haircut arrived pre-enactment with no published methodology — a rare case of a government self-flagging a contestable assumption.
- The ballot-language effect dwarfs the campaigns. [UPDATED — extends last cycle's DHM polling detail with fresh numbers] A single legally mandated fiscal-impact sentence moved Washington opinion by 13 points — more than any ad war washington-state-wealth-tax-study-and-constitutional-constraints+1.
Open threads
Closed/absorbed from last time:
- The Washington Supreme Court elections watch thread has been absorbed into the body — the court-seats-on-the-ballot fact now lives as a passing mention in the Washington section, with no separate tracking vote.
Current threads:
- [watch] Hungary parliament enacts (or stalls) the wealth tax before its Jan 1, 2027 start — does the bill pass with the announced design, and does an official fiscal score appear? Threads
- [watch] If Prop 40 passes: first constitutional challenge filing and FTB implementation steps. Threads
- [question] Adjudicate the Prop 40 revenue models: Hoover's -$25B vs proponents' +$100B, against NBER Norway evidence. Threads