California Proposition 40 billionaire tax calculator
Proposition 40, on the November 3, 2026 ballot, is a one-time tax of 5% of the entire net worth of California residents (as of January 1, 2026) worth $1 billion or more, valued December 31, 2026. This calculator scores it person by person from Forbes data and shows what each contested assumption is worth, including the ones behind the Berkeley and Hoover estimates.
What separates the published estimates
Berkeley assumptions +$103.2B → Hoover assumptions -$34.3B, on the same people, Forbes data as of 2026-10-23, net present value as of 2026. Each bar is one assumption's worth, averaged over every order the assumptions could be applied in, so the bars sum exactly to the gap. Click a bar to change that assumption.
Statutory score: One-time wealth-tax revenue
Present value as of 2026: +$114.2B
Nominal receipts, first due with 2026 returns in 2027. Excludes future California income-tax losses. Forbes as of Oct 23, 2026, 6:05 AM PDT.
Start from
The Legislative Analyst's Office expects “tens of billions of dollars spread over several years” and calls an ongoing income-tax decrease of “less than $1 billion per year” possible.
Since October 21, 2026 the Hoover assumptions follow Jaros and Rauh's NBER version (a 50% chance the measure survives legal challenge, Mark Zuckerberg and non-US citizens out of the base, and 45% of the cohort's income tax lost); before, they followed Rauh et al.'s March 2026 paper.
Who pays the income tax matters when the largest fortunes are the movers
Net present value as of 2026 with income-tax effects counted, across how much of the reachable base left before January 1 without public notice and how much California income tax the cohort pays in total. Same axes, same colors, two ways of dividing that total among people. Other assumptions as in your scenario. The two grids coincide right now: with no documented departure applied, the unannounced share takes the same slice of everyone's income tax under either division. Apply a departure claim in the residency panel and the grids separate.
Divided by wealth (Rauh et al.)
Filings for the four largest fortunes, the rest by wealth
Who pays
Everyone Forbes listed in California on January 1, 2026, valued at their Forbes worth on 2026-10-23 wherever Forbes lists them, plus everyone Forbes has added to its California list since.
Known separately listed spouses (Jay-Z and Beyoncé; Lynda and Stewart Resnick) share one wealth-tax threshold and rate, including both spouses' observed assets if either remains a resident. The table allocates joint liability to their asset shares; income tax stays person-based. Other unobserved spouse and minor-child assets are not available in Forbes data.
Derivation
- 272 people are in the tax base under the current assumptions.
- 59 people ($262.7B) are on Forbes' California list now and were not on its January 1, 2026 list. They are assumed to have been California residents on January 1.
- 8 people ($583.0B) were on Forbes' California list on January 1, 2026 and are listed elsewhere now. They stay in the base at their current Forbes worth unless removed under residency.
- 10 people ($25.0B) from the January 1 list are no longer on any Forbes list. They are carried at the last positive value in the stored daily Forbes history.
- 4 people are under $1 billion and out of the base, 2 of them only once directly held real estate is removed.
- The January 1 list is rebuilt from US-citizen Forbes profiles, so the 25 non-US citizens Forbes now places in California ($154.3B) enter only through the current list, with their January 1 residency assumed. Galle, Gamage, Saez and Shanske add the same group.
The income-tax column is what each person pays a year. The derivation's lost income tax is the rows of people removed or marked as leaving, plus the modeled share of everyone else's, times the attribution rate.
| Name | Net worth | RE excluded | Rate | Wealth tax | CA income tax/yr |
|---|---|---|---|---|---|
Larry Page Pre-snapshot departureForbes now lists Florida Real estate holdings: $102M excluded from taxable wealth | $266.6B | $102M | 5.0% | $13.3B | $57M |
Sergey Brin Pre-snapshot departureForbes now lists Nevada Real estate holdings: $35M excluded from taxable wealth | $245.4B | $35M | 5.0% | $12.3B | $37M |
Mark Zuckerberg Post-snapshot departure Real estate holdings: $300M excluded from taxable wealth | $222.8B | $300M | 5.0% | $11.1B | $101M |
Jensen Huang Real estate holdings: $52M excluded from taxable wealth | $183.9B | $52M | 5.0% | $9.2B | $57M |
Peter Thiel Pre-snapshot departureForbes now lists Buenos Aires Real estate holdings: $77M excluded from taxable wealth | $37.3B | $77M | 5.0% | $1.9B | $104M |
Eric Schmidt Real estate holdings: $600M excluded from taxable wealth | $36.6B | $600M | 5.0% | $1.8B | $102M |
Andreas von Bechtolsheim & family Not on the Jan. 1 list; residency assumed Real estate holdings: $223M (imputed at 0.64% of net worth) excluded from taxable wealth | $34.9B | $223M | 5.0% | $1.7B | $97M |
Henry Samueli Real estate holdings: $20M excluded from taxable wealth | $30.9B | $20M | 5.0% | $1.5B | $86M |
John Tu Real estate holdings: $7.3M excluded from taxable wealth | $30.1B | $7.3M | 5.0% | $1.5B | $84M |
David Sun | $30.1B | — | 5.0% | $1.5B | $84M |
Robert Pera Real estate holdings: $22M excluded from taxable wealth | $29.6B | $22M | 5.0% | $1.5B | $83M |
Greg Brockman Not on the Jan. 1 list; residency assumed Real estate holdings: $163M (imputed at 0.64% of net worth) excluded from taxable wealth | $25.5B | $163M | 5.0% | $1.3B | $71M |
Brett Adcock | $23.4B | — | 5.0% | $1.2B | $65M |
John Doerr | $21.9B | — | 5.0% | $1.1B | $61M |
Henry Nicholas III Real estate holdings: $20M excluded from taxable wealth | $20.6B | $20M | 5.0% | $1.0B | $58M |
Donald Bren | $19.8B | — | 5.0% | $990M | $55M |
Jan Koum Reported departure Real estate holdings: $400M excluded from taxable wealth | $18.6B | $400M | 5.0% | $910M | $52M |
Eric Smidt Real estate holdings: $54M excluded from taxable wealth | $17.8B | $54M | 5.0% | $885M | $50M |
John Collison Not on the Jan. 1 list; residency assumed Real estate holdings: $112M (imputed at 0.64% of net worth) excluded from taxable wealth | $17.5B | $112M | 5.0% | $869M | $49M |
Patrick Collison Not on the Jan. 1 list; residency assumed Real estate holdings: $112M (imputed at 0.64% of net worth) excluded from taxable wealth | $17.5B | $112M | 5.0% | $869M | $49M |
| Included total (272 of 276) | $2367.9B | $117.7B | $4.3B |
Related work
Two other analyses compare versions of the Berkeley and Hoover estimates. This calculator's Berkeley and Hoover starting points do not reproduce either team's calculation: they apply assumptions from Galle, Gamage, Saez and Shanske and from Rauh et al. as settings inside one person-by-person model, starting from the same Forbes snapshot.
Fernando Hoces de la Guardia, “California Proposition 40, Reconciliation of the Two Analyses” (Open Policy Analysis report, October 2026).
Puts the Boll, Saez and Zucman analysis (NBER, August 2026) and the Jaros and Rauh analysis (NBER, September 2026) on one common output, using the project's own reproduction of each, and explains the gap between them one disputed input at a time. The first builds on the Galle, Gamage, Saez and Shanske report; the second revises Rauh et al.'s March 2026 paper. Its appendix discusses this calculator.
Jeffrey L. Hoopes, “Galle v Rauh: Comparing Two Revenue Estimates for California Billionaire Taxation” (SSRN Working Paper 6428578, March 2026).
Compares the methods behind the 2026 revenue estimates by Galle, Gamage, Saez and Shanske and by Rauh, Jaros, Kearney, Doran and Cosso.