WealthTaxWatch

California’s narrow opening

Proposition 40 would impose a one-time 5% tax on the net worth of billionaires who were California residents on January 1, 2026, with most revenue directed to health care. The Legislative Analyst projects a temporary gain of tens of billions of dollars over several years, plus a possible ongoing income tax loss if some billionaires leave. The sponsoring union, SEIU-UHW, puts the figure near $100 billion; treat that as a campaign estimate, not an official one.

Vote: November 3 · Ballots mailed from October 5

Sources: PPIC survey ↗ · UC Berkeley IGS poll ↗ · CalMatters on Newsom and Prop 42 ↗

Cooperation, without a common tax

BRICS. The New Delhi Declaration, adopted September 12, welcomes two new working groups (international taxation and transfer pricing; revenue statistics). At a BRICS tax heads meeting on September 23, India’s finance minister argued that BRICS must shape the rules now being renegotiated, including in the UN convention talks. None of this commits members to a shared wealth tax.

G20. Under the US presidency, the Asheville meeting (August 31 to September 1) ended with a chair’s statement rather than an agreed communiqué. It focuses on growth, debt, payments and digital assets, and contains no language on taxing ultra-high-net-worth individuals. That is a visible retreat from the 2024 Rio declaration, in which G20 ministers said they would engage on the issue. Silence in a chair’s statement does not establish individual members’ positions.

UN tax convention. The first complete draft texts (the framework convention and two early protocols, on cross-border services and on tax disputes) were released on July 20 and 21. Delegations began line-by-line negotiation at the fifth session in New York, August 3 to 13, with finalisation targeted for 2027. According to Tax Justice Network’s session recap, some delegations pushed for clearer commitments on taxing high-net-worth individuals; the early protocols themselves do not address wealth taxation.

Inequality panel. South Africa, Brazil, Norway and Spain hosted a high-level event on September 23 to launch a proposed International Panel on Inequality, modelled on the IPCC and growing out of the Stiglitz-chaired G20 inequality committee. It is an evidence and coordination body, not a tax instrument.

Sources: G20 chair’s statement ↗ · UN tax convention negotiations ↗ · International Panel on Inequality event ↗

A modest wealth levy within a wider reform

On September 21 the Cour des comptes published a note on household wealth taxation with sixteen recommendations. It argues that France’s wealth taxation, despite high headline rates, becomes regressive at the very top because of exemptions. The note draws heavily on the December 2025 report of the Conseil des prélèvements obligatoires, which modelled a differential charge on non-business wealth alongside the existing real-estate wealth tax (IFI). This is distinct from the 2% minimum on fortunes above €100 million, often called the Zucman tax, which the Cour does not adopt.

The package pairs tax increases (the differential wealth charge, a stronger tax on personal holding companies, narrower Pacte Dutreil relief for family businesses) with cuts: about €1.1 billion less in property transaction duties and a five-point cut across inheritance and gift tax brackets worth about €2.1 billion. The Cour puts the net effect at €1.83 billion, falling only on the largest fortunes. Where the CPO’s scenarios were revenue-neutral, the Cour’s version raises revenue. These are recommendations timed for the 2027 budget bill, which the government presents to cabinet on September 30. Prime Minister Sébastien Lecornu has promised tax stability and “no new tax”, and has announced a new business-transfer scheme, the “pacte Papin”; how it relates to the Pacte Dutreil relief the Cour wants to narrow is not yet clear. AFP report on the presentation ↗ · Senate reaction (Public Sénat) ↗ · Lecornu’s budget announcements ↗

The Zucman tax returns. On September 16 the Socialist Party presented an alternative budget built around the Zucman tax: a 2% minimum tax on fortunes above €100 million, which the Assemblée nationale rejected in October 2025 by 228 votes to 172. It is an opposition proposal, not a government measure, and it runs against the prime minister’s “no new tax” line. It can only be put to a vote as an amendment once the budget bill reaches Parliament, after September 30.

More debate than adoption

The OECD’s Tax Policy Reforms 2026, published September 8, covers measures introduced or announced during 2025 in 92 jurisdictions. Property tax reforms leaned more towards raising revenue than in past years, mainly through recurrent taxes on immovable property, while changes to net wealth taxes remained limited. The release date should not be confused with the period the data cover.

The European Commission’s April study (two volumes, with case studies from Austria, France, Germany, Spain, Norway, Switzerland and Colombia) finds that the wealth taxes examined were not major revenue sources, and attributes much of the shortfall to reliefs, exemptions and weak compliance. It stresses beneficial ownership data, asset registers and third-party reporting, and makes no policy recommendation.

On September 23 the Tax Justice Network launched an updated illicit financial flows tracker. It estimates that about US$673 billion crosses European borders each year for tax abuse purposes, mostly into other European countries, and that wealthy individuals and multinationals keep roughly US$100 billion a year that would otherwise be paid in tax. That is a modelled estimate of tax abuse, not projected wealth tax revenue.

Sources: OECD Tax Policy Reforms 2026 ↗ · European Commission study ↗ · Tax Justice Network tracker ↗

Several routes to taxing wealth

The CCPA’s Alternative Federal Budget 2026-27 taxation chapter, released September 16, proposes an annual progressive tax on net worth above C$10 million, estimated to raise more than C$39 billion in its first year and to leave 99.4% of Canadians unaffected. The estimate rests on Oxfam Canada modelling from January 2026; the previous edition, published in October 2025, cited about C$37 billion.

The chapter also costs four related measures: a 50% tax on lifetime inheritances above C$2.5 million (about C$1.1 billion a year); a 37% federal bracket on income above C$1 million (about 45,000 filers and C$1.4 billion in 2027); full inclusion of inflation-adjusted capital gains (about C$13 billion a year); and C$2 billion over three years for CRA enforcement, against planned CRA job cuts.

These tax holdings, transfers, income and gains, each with different valuation and enforcement problems, and the estimates are advocacy costings rather than PBO or Finance Canada scores. None is current federal policy. Ottawa now tables its budget in the fall: Budget 2026 is due this autumn, and no date has been announced. CCPA taxation chapter ↗

Three different ways to tax wealth

Context: Chancellor John Healey presents his first budget on October 28 under Prime Minister Andy Burnham.

Annual net wealth. Compass’s Ending Business as Usual, published in early September, collects 70 policy options from 15 contributors and calls itself a menu, not a manifesto. It includes Tax Justice UK’s proposal for a 2% annual tax on net assets above £10 million, estimated at up to £24 billion a year. A parliamentary petition for the same tax followed a “Proud to Pay” letter from 120 UK millionaires. This is advocacy, not an announced government measure.

A minimum for the very wealthiest. A July International Tax Observatory study by Ben Tippet and Gabriel Zucman proposes that households worth more than £100 million pay at least 2% of their wealth each year in total personal taxes, with taxes already paid counting towards it. It estimates about £10.4 billion in 2026 from fewer than 1,000 households, after avoidance and behavioural responses, and includes a ten-year post-emigration liability. The £10 billion and £24 billion figures use different thresholds, tax units and mechanisms; do not add them together.

Existing capital and property taxes. Compass also proposes a capital gains overhaul, including rate alignment with income tax and ending the uplift at death. The Institute for Fiscal Studies has long argued that valuation and avoidance make an annual wealth tax hard to run and favours reforming taxes on capital income and transfers instead. Separately, the Resolution Foundation’s September report Home Economics proposes replacing Council Tax and Stamp Duty on primary residences with a revenue-neutral 0.7% annual tax on current property value, paid by occupiers, with rebates for low-income households and deferral for the asset-rich but cash-poor. It finds Londoners underpay by about £3.1 billion relative to the rest of England, and warns that abolishing Stamp Duty alone would leave a £15 billion hole. That is a property tax reform, not a net wealth tax.

Sources: Taxing Extreme Wealth in the UK ↗ · Resolution Foundation, Home Economics ↗