Prop. 40 Without the Commercials: What California's Billionaire Tax Actually Says

I have been seeing a lot of commercials about California Proposition 40 lately, and depending on which commercial you watch, you would think we are voting on two completely different laws.

One side describes it as a straightforward one-time tax on billionaires that will raise roughly $100 billion.

The other warns that it is really a tax on every Californian, that everyone will have to disclose their finances under penalty of perjury, that retirement accounts are being taxed, and that the Legislature will be able to expand the tax to everyone later.

Those claims cannot all describe the same law.

So I stopped listening to the commercials and read the measure.

That turns out to be particularly important here because the California Secretary of State explicitly warns voters that the arguments for and against ballot propositions are the opinions of their authors and have not been checked for accuracy by any official agency. (California Secretary of State)

Here is what Proposition 40 actually says.

First: this really is a wealth tax aimed at billionaires

The official title is Imposes One-Time Tax on Certain Taxpayers. Initiative Constitutional Amendment and Statute.

The measure adds a new Part 27 to California's Revenue and Taxation Code. Section 50301(a) applies the tax for the 2026 tax year to qualifying individuals with net worth of at least $1 billion and to certain trusts.

So the claim that Proposition 40 currently imposes a wealth tax on every Californian is not supported by the text.

The Legislative Analyst's Office describes it the same way: a one-time wealth tax on billionaires who were California residents on January 1, 2026. (Legislative Analyst's Office)

But there is an important detail that gets lost when people simply call this a "5 percent tax on wealth over $1 billion."

That isn't quite how the formula works.

Section 50301(b) starts with a tax of 5 percent of the taxpayer's net worth as defined by the measure. For individuals between $1 billion and $1.1 billion, that rate is phased in by reducing it 0.1 percentage point for every $2 million below $1.1 billion. At $1 billion the resulting rate is zero; at $1.1 billion it reaches the full 5 percent. (California Attorney General)

That means, roughly:

That distinction matters. Once the phase-in is complete, the 5 percent applies to the taxable net worth defined by the measure, not merely the dollars above $1 billion.

Does everyone have to report their wealth?

This is where the opposition commercials contain a real fact wrapped in misleading language.

Section 50301(d) does apply a new declaration requirement much more broadly than the tax itself.

It says that when the 2026 California income-tax return is filed, every California resident who is required to file a return must do one of two things:

1. Declare that their net assets were worth $1 billion or less on the valuation date; or
2. If applicable, submit the wealth-tax calculation, forms and required valuation evidence.

That is really in the measure. It isn't something opponents invented. (California Attorney General)

But that is very different from saying every Californian must prepare an inventory of everything they own.

For an ordinary taxpayer, the measure itself requires a declaration that net assets are $1 billion or less. It does not say that everyone must list their bank balances, calculate the value of their house, disclose their retirement account balance, or submit an exact personal net-worth statement.

So there are two separate questions that shouldn't be blended together:

Who pays the wealth tax? People and certain trusts meeting the billionaire threshold.

Who gets a new filing requirement? California residents required to file a 2026 income-tax return.

Both statements can be true at the same time.

What about "under penalty of perjury"?

This claim also needs context.

Section 50301(d) itself does not create a special new sentence saying that every Californian must swear their net worth under penalty of perjury.

California income-tax returns are already signed that way.

The current Form 540 requires taxpayers to certify under penalties of perjury that the return, including accompanying schedules and statements, is true, correct and complete. (State of California Franchise Tax Board)

Proposition 40 then instructs the Franchise Tax Board in Section 50309(c) to amend California's personal income-tax forms and create whatever additional forms are necessary to implement the measure. (California Attorney General)

So there is a legitimate point underneath the advertising: the new billion-dollar declaration is being inserted into an existing tax-return system that taxpayers already certify under penalty of perjury.

But describing this as Proposition 40 creating some entirely new perjury oath for every Californian leaves out the fact that we already certify our state tax returns that way.

And I've also heard the declaration described as requiring people to testify to their "total income."

That is simply the wrong thing.

Section 50301(d) concerns whether net assets exceed $1 billion. Income and wealth are different things. California taxpayers already report income on their normal state tax returns.

Is your house being taxed?

Not under the measure as written.

Section 50303(c)(4) specifically excludes interests in real property held directly by the taxpayer or through a revocable trust from the net-worth calculation. (California Attorney General)

The Attorney General's official ballot summary likewise says covered assets include things such as businesses, securities, art, collectibles and intellectual property, while real property is excluded. (California Secretary of State)

That doesn't mean real estate can never indirectly affect the value of a business or another asset. The measure has detailed valuation rules for business interests and trusts. But the statement that Proposition 40 itself imposes a 5 percent tax on everyone's home equity is not what the text says.

What about retirement accounts?

The broad claim that Proposition 40 taxes everyone's retirement savings is also not supported by the measure.

Section 50303(c)(7) expressly exempts qualified pensions and individual retirement arrangements from both taxation under this part and the asset-reporting requirements in that section.

There is an exception for Roth IRAs and similar Roth arrangements once their aggregate value exceeds $10 million. Certain nonqualified compensation arrangements can also be treated differently. (California Attorney General)

So "Prop. 40 taxes retirement accounts" is missing a rather important qualification.

For ordinary retirement accounts, the measure expressly provides an exemption.

Can the Legislature expand this tax to everyone later?

This is probably the most complicated claim in the advertising because it mixes something the measure clearly allows with speculation about how far that authority extends.

Section 50310 says the Legislature may amend the Billionaire Tax Act without another statewide vote if the amendment passes each house by a two-thirds vote.

That part is true.

But the same sentence imposes another requirement: the amendment must be consistent with and further the purposes of the 2026 Billionaire Tax Act. (California Attorney General)

And Section 3 describes those purposes as raising revenue through a narrowly applicable, one-time tax on billionaire wealth. The constitutional language similarly says the measure authorizes a one-time tax on the accumulated wealth of California billionaires. (California Attorney General)

That means the proposition does not contain language simply saying, "The Legislature may later impose this wealth tax on anyone it chooses."

Could some future Legislature attempt to stretch its amendment authority? Of course. Legislatures and initiative proponents end up in court over questions like that all the time.

Whether some hypothetical future expansion would still be legally "consistent with and further" the purposes of the initiative would ultimately be a legal question.

But that hypothetical possibility should not be presented as though the current measure already imposes a wealth tax on ordinary Californians. It doesn't.

The Franchise Tax Board does get substantial enforcement authority—but much of it already exists

Section 50301(e) tells the Franchise Tax Board to examine returns submitted under the measure and also allows it to examine taxpayers' certifications or returns when it reasonably believes they should have paid the wealth tax.

The section specifically gives the FTB the powers already contained in Revenue and Taxation Code Section 19504. (California Attorney General)

Those existing powers are substantial.

Section 19504 already allows the FTB to demand relevant books, papers and other information from people, employers and financial institutions, require testimony, administer oaths and issue subpoenas. (LegiInfo)

That distinction matters too.

Proposition 40 is not inventing all of those investigative powers from scratch. California tax law already gives them to the FTB.

What Proposition 40 does is explicitly make those existing powers available when the FTB investigates whether someone should have paid this particular wealth tax.

There are some unusually aggressive implementation provisions

There are parts of Proposition 40 that deserve scrutiny without anyone needing to exaggerate them.

For example, Section 50309 temporarily exempts FTB regulations and guidance implementing the measure from the normal rulemaking requirements of California's Administrative Procedure Act until January 1, 2028.

It also gives the FTB as long as ten years after a return is filed to mail certain proposed deficiency assessments relating to the 2026 tax year.

Those aren't campaign predictions. They're in Section 50309.

The timing is also unusual

The election is November 3, 2026.

But Section 50308 defines the tax obligation date as January 1, 2026, while the valuation date is December 31, 2026. (California Attorney General)

In other words, California residency at the beginning of 2026 can determine whether someone falls within the measure even though voters will not decide Proposition 40 until November.

The measure anticipates that the timing could face a legal challenge. Section 50311 tells courts, where legally possible, to adjust problematic dates rather than invalidate the whole tax and to preserve a 2026 tax—or, if that cannot legally be done, move it to the earliest permissible later year. (California Attorney General)

That is a real feature of the proposition and something voters can reasonably consider.

How much money would it actually raise?

This is another place where campaign advertising gets ahead of what the state's own analysts are willing to say.

Supporters state in the official voter guide that Proposition 40 will raise about $100 billion.

The nonpartisan Legislative Analyst's Office does not make that prediction.

Its estimate is that the wealth tax would probably generate tens of billions of dollars spread over several years, while acknowledging that the amount is unusually difficult to predict because asset values change and taxpayers could alter their behavior. (California Secretary of State)

The LAO also estimates that behavioral changes—including some billionaires leaving California—could cause an ongoing reduction of less than $1 billion per year in existing state income-tax revenue. Administration could cost tens of millions of dollars annually for several years. (Legislative Analyst's Office)

Those are estimates, not guarantees.

Where does the money go?

After administrative expenses, the measure places the revenue in a separate Billionaire Tax Reserve Fund.

Ninety percent goes to a health-care account. Ten percent goes to education and food assistance. The measure also prevents this money from simply replacing existing state appropriations for those purposes. (California Constitution, proposed Article XIII §37; Government Code §16355.)

The proposition deliberately excludes this revenue from some existing constitutional rules governing the state spending limit, budget reserves and school funding calculations. The Legislative Analyst calls that out in its official analysis. (Legislative Analyst's Office)

Whether voters think that structure is a good idea is a policy judgment. But that's the structure actually being proposed.

So what is Proposition 40?

After reading the measure, I think the simplest factual description is this:

Proposition 40 creates a one-time wealth tax targeted at California billionaires, while also requiring every California resident who must file a 2026 income-tax return to declare whether their net assets exceed $1 billion.

It gives the Franchise Tax Board significant authority to implement and enforce that tax, largely by extending existing tax-administration powers into this new area.

It excludes directly held real estate and most ordinary retirement accounts.

It allows a two-thirds Legislature to amend the Act, but requires those amendments to remain consistent with and further the purposes of a measure explicitly written around a one-time tax on billionaire wealth.

And the state's own nonpartisan analysts estimate revenue in the tens of billions of dollars, not a guaranteed $100 billion.

That's considerably more complicated than either thirty-second commercial.

The supporter argument that this affects only billionaires leaves out the fact that millions of ordinary California tax filers would receive a new billion-dollar net-assets declaration on their tax return.

The opponent argument that Proposition 40 itself taxes everyone's savings, homes and retirement accounts goes much further than the text of the measure supports.

And claims about what a future Legislature might attempt are not the same thing as describing what Proposition 40 actually does today.

I'm not interested in telling anyone how to vote on it.

But if we're going to decide something this consequential, we should at least be deciding based on the law that is actually printed on the ballot—not the version of it somebody bought thirty seconds of television time to sell us.

Primary sources

Full text of Initiative 25-0024A1, the 2026 Billionaire Tax Act — California Attorney General: Sections 3, 50301, 50303, 50308, 50309, 50310 and 50311 are the provisions discussed above. California Attorney General — full Proposition 40 initiative text

California Legislative Analyst's Office — Proposition 40 impartial analysis: fiscal estimates and plain-language description of the proposal. Legislative Analyst's Office — Proposition 40 analysis

California Secretary of State — Official Voter Information Guide: includes the Attorney General's summary, LAO analysis and the competing campaign arguments. Importantly, the state labels those campaign arguments as opinions that have not been officially fact-checked. Official Proposition 40 voter guide

California Franchise Tax Board — current Form 540: shows the existing penalty-of-perjury certification for California resident income-tax returns. California Form 540

California Revenue and Taxation Code §19504: existing Franchise Tax Board examination, information-demand, testimony and subpoena authority incorporated by Proposition 40. California Revenue and Taxation Code §19504