As betting markets currently put the odds of California voters approving a “one-time” tax on the assets of billionaires at about 30 percent, the downstream risk of proposals like this is that they will eventually make their way into federal legislation.
In fact, they already have. Earlier this year Senator Bernie Sanders and representative Ro Khanna introduced the Make Billionaires Pay Their Fair Share Act. The legislation would impose a 5 percent annual tax on the wealth of the nations 989 billionaires.
Punishing private wealth creation
The first thing to recognize, is that the billions of dollars in wealth held by the almost 1,000 billionaires in the U.S. isn’t cash that is being hoarded under a mattress waiting to be taxed. For instance, Elon Musk’s roughly $900 billion fortune is mostly stock held in SpaceX and Tesla.
What’s more, Musk’s personal fortune represents only about one-third of the combined value of the companies he has founded.
The remaining two-thirds is represented by factories, equipment, intellectual property, business assets, and claims held by other shareholders, including pension funds, mutual funds, and ordinary Americans who own shares directly or indirectly. The companies also employ tens of thousands of workers whose wages support household incomes and consumption.
For other billionaires, the share of wealth kept for themselves versus the share granted as value created for wider society is even larger than that of Musk. Mark Zuckerberg’s personal fortune represents about 13 percent of the market value of Meta. The other 87 percent is owned by shareholders, ordinary investors, or represented as data centers, servers, other productive assets, and nearly 79,000 employees.
In other words, the wealth of billionaires is a small share of the trillions of dollars in private wealth that they have created for millions of ordinary American’s. The free enterprise system rewards this kind of entrepreneurial activity and innovative behavior that in turn promotes productivity and growth. Removing these rewards by confiscating their personal assets and handing them over to the state would instead punish such activity.
A 5 percent wealth tax is a 99 percent income tax
The second thing to recognize is that the proposed 5 percent tax on wealth is a much larger tax on the returns of investments.
Consider the average market return over the 25 years between 2000 and 2025. Assuming dividends are reinvested, this comes out to 8.17 percent. With this return, the 5 percent wealth tax is a 61 percent tax on investment returns.
But we also have to account for the invisible tax that we all pay—inflation. Once inflation is factored in, market returns drop to 5.48 percent. At that level, the wealth tax is a 91 percent tax on investment returns. If we also assume that capital gains taxes are applied to dividends, then the after-tax return drops to just 5.05 percent. In this case, the wealth tax is effectively a 99 percent tax on investment income.
A 99 percent tax on investment income will have a significant impact on the incentives of investors. One of the incentives that will undoubtedly change is that people will take less risks. Low risk investments have lower rewards, and this will be felt by everyone, not just the billionaires that the policy targets.
Slower capital formation, weaker productivity, lower wages and fewer opportunities for workers and businesses affect all workers and consumers, not just wealthy ones.
We already have a wealth tax of sorts
As Stanford economist John Cochrane recently pointed out on his Substack, the U.S. already taxes wealth in certain circumstances. For example, the estate tax applies to the assets of the deceased when it is passed onto an heir.
Importantly, I should point out that a tax on the transfer of property is very different to a tax recurring tax on property ownership. The Supreme Court has also made a strong distinction between these types of taxes too, as it considers the estate tax an indirect excise tax on the transfer of property.
As Cochrane points out, the estate tax attracts a significant amount of perfectly legal avoidance. Although the tax applies at a much lower threshold than the proposed wealth tax, at $13.99 million, the Treasury estimates, that combined with gift tax receipts, the estate tax raised $29 billion in revenue in FY2025, or less than 0.1 percent of GDP.
Even a study published by supporters of a wealth tax found that the estate tax collects just 300-to-400ths of a percent annually of the Forbes 400 wealth.
The revenue gain is about $200 billion a year
So how much revenue do proponents of a wealth tax suggest it would raise if implemented in the U.S.?
French economists Emmanuel Saez and Gabriel Zucman estimate that a 5 percent wealth tax will raise $4.4 trillion over 10 years. To get this figure, they assume a tax evasion rate of 10 percent. This implies an elasticity of taxable wealth around -2. This assumption is significantly out-of-whack with the bulk of economic literature.
Evidence of savings effects based on Norwegian micro data estimate elasticities of taxable wealth around -7 under a comprehensive tax base. Similarly, evidence from Switzerland using cantonal variation finds that a one-percentage-point reduction in the wealth-tax rate increased reported taxable wealth by at least 43 percent after six years.
One 2021 journal article used rich administrative data from Colombia and a government-designed program for voluntary disclosures of hidden wealth to estimate the behavioral effects of wealth tax. The authors found that two-fifths (40%) of the wealthiest 0.01 percent evade taxes, with these evaders concealing one-third of their wealth offshore.
Using Danish administrative data, Jakobsen et al. find that reductions in the wealth tax increased taxable wealth by 31 percent among the very wealthy over eight years. Their estimates incorporate saving, portfolio and asset-composition responses, legal avoidance, and possible evasion of self-reported assets. The net-of-tax rate elasticity is therefore estimated at around -11.
With these estimates in mind, budget scoring organizations often use more realistic elasticity estimates that are more aligned with the economic literature. For example, the Tax Foundation models wealth tax proposals using a semi-elasticity assumption of -8, while Penn Wharton applies semi-elasticities of evasion and avoidance around -9.
If we replace the elasticity assumptions of Saez and Zucman with a more realistic semi-elasticity of around -8, then the revenue raised by the tax drops from $4.4 trillion to $3.3 trillion over 10 years. This isn’t an outlier assumption. In fact, Sanders and Warren used a 33% avoidance assumption in their 2020 wealth tax campaigns.
Factoring in baseline avoidance in the existing tax system and stronger behavioral responses, tax scholar Kyle Pomerleau applies an elasticity of -13. This results in a 10-year revenue yield of $2.3 trillion, or roughly half the Saez-Zucman figure. This amounts to a little over $200 billion a year in additional revenues, or about 10 percent of current deficits.
A high price for the U.S. economy
A 5 percent wealth tax isn’t just a tax on billionaires, it is a tax on investment, a tax on risk-taking, a tax on capital accumulation that drives productivity, higher wages, and job growth. The people who ultimately bear those costs would include workers, consumers, retirees, and the millions of ordinary Americans whose savings are invested in the companies billionaires helped build.
Wealth is not cash sitting idle in a bank account. It is the factories, companies, technologies, and investments that generate future income for millions of people. Taxing wealth at punitive rates may satisfy a desire to punish the rich, but it risks shrinking the very economic base from which future prosperity will come.
Let’s not tax away our productivity, innovation, and growth for the sake of political symbolism.