And how to limit the economic damage
.. If revenues are to rise, there are good grounds to look first to the rich. Mr Trump’s tax cuts are just the latest change to have made life at the top more splendorous. Between 1990 and 2015 the real income of the top 1% of households, after taxes and transfers, nearly doubled. Over the same period middle incomes grew by only about a third—and most of that was thanks to government intervention. Globalisation, technological change and ebbing competition have all helped the rich prosper in recent decades. Techno-prophets fear that inequality could soon worsen further, as algorithms replace workers en masse. Whether or not they are right, the disproportionate gains the rich have already enjoyed could justify raising new revenues from them.
Unfortunately, the proposed new schemes are poorly designed. Ms Warren’s takes aim at wealth inequality, which has also risen dramatically. It is legitimate to tax wealth. But Ms Warren’s levy would be crude, distorting and hard to enforce. A business owner making nominal annual returns of around 5% would see much of that wiped out, before accounting for existing taxes on capital. That prospect would squash investment and enterprise. Meanwhile, bureaucrats would repeatedly find themselves having to value billionaires’ art collections and other illiquid assets. Eight rich countries have scrapped their wealth taxes since 1990, often amid concerns about their economic and administrative costs. In 2017 only four levied them.
There are better ways to raise taxes on capital. One is to increase inheritance tax, an inequality-buster that, though also too easily avoided, is relatively gentle on investment and work incentives when levied at modest rates. Another is to target economic rents and windfalls that inflate investment returns. Higher property taxes can efficiently capture some of the astronomical gains that landowners near successful cities have enjoyed. It is also possible to raise taxes on corporations that enjoy abnormally high profits without severely inhibiting growth. The trick is to shield investment spending by letting companies deduct it from their taxable profit immediately, rather than as their assets depreciate. (Mr Trump’s reform accomplished this, but only partially and temporarily.)
.. What about income tax? Ms Ocasio-Cortez’s boosters point out that a 70% levy is close to the rate that is said to maximise revenue in one notable economic study. In truth the study is notable because it is an outlier—one that ignores the benefits of entrepreneurial innovation or of workers improving their skills. France’s short-lived 75% top tax rate, which was scrapped at the end of 2014, raised less money than was hoped. America’s top rate of federal income tax is 37%; higher is clearly feasible, but it would be wise to keep change incremental.
Although there is scope to raise taxes on the rich, they cannot pay for everything, if only because the rich are relatively scarce. One estimate puts extra annual revenue from Ms Ocasio-Cortez’s idea, which applies only to incomes above $10m, at perhaps $12bn, or 0.3% of the tax take. Ms Warren’s proposal would raise $210bn a year, her backers say—but they assume, implausibly, limited avoidance and no economic damage. Ultimately, the price of ambitious spending programmes will be tax increases that are also far-reaching. The crucial point about a strategy for taxing the rich is to realise that it has limits.