To Reduce Inequality, Tax Wealth, Not Income WHETHER you're in the 99 percent, the 47 percent or the 1 percent, inequality in America may threaten your future. Often decried for moral or social reasons, inequality imperils the economy, too; the International Monetary Fund recently warned that high income inequality could damage a country's long-term growth. But the real menace for our long-term prosperity is not income inequality - it's wealth inequality, which distorts access to economic opportunities. Wealth inequality has worsened for two decades and is now at an extreme level. Replacing the income, estate and gift taxes with a progressive wealth tax would do much more to reduce it than any other tax plan being considered in Washington. When economists try to measure inequality, they typically focus on income, because the data are most readily accessible. But income is not always a good gauge of economic power. Consider a group of people who all have high incomes but differ widely in their wealth. Who's going to get into the country club? Who's going to have the money to finance a new venture? Moreover, income data may not reveal the true economic power of people who are retired, or who receive their pay in securities like stocks and options or use complex strategies to avoid taxes. Trends in the distribution of wealth can look very different from trends in incomes, because wealth is a measure of accumulated assets, not a flow over time. High earners add much more to their wealth every year than low earners. Over time, wealth inequality rises even as income inequality stays the same, and wealth inequality eventually becomes much more severe. This is exactly what happened in the United States. A common statistical measure of inequality is the Gini coefficient, a number between 0 and 100 that rises with greater disparities. From the late 1970s through the early 1990s, the Census Bureau recorded Gini coefficients for income in the low 40s. Yet by 1992, the Gini coefficient for wealth had risen into the mid-70s, according to data from the Federal Reserve. Since then, it has risen steadily, to about 80 as of 2010. In 1992, the top tenth of the population controlled 20 times the wealth controlled by the bottom half. By 2010, it was 65 times. Our graduated income-tax system redistributes a small amount of money every year but does little to slow the polarization of wealth. These are stunning changes. The global financial crisis did make a dent in the assets of the wealthiest American families, but its effects for the bottom half were utterly destructive; the number of owner-occupied homes has fallen by more than a million since 2007. People in different socioeconomic strata are living ever more different lives, with dangerous results for society: erosion of empathy, widening of rifts and undermining of meritocracy. American household wealth totaled more than $58 trillion in 2010. A flat wealth tax of just 1.5 percent on financial assets and other wealth like housing, cars and business ownership would have been more than enough to replace all the revenue of the income, estate and gift taxes, which amounted to about $833 billion after refunds. Brackets of, say, zero percent up to $500,000 in wealth, 1 percent for wealth between $500,000 and $1 million, and 2 percent for wealth above $1 million would probably have done the trick as well. These tax rates would garner a small portion of the extra wealth America's richest families could expect to accrue simply by investing what they already had. The rates would also be enough to slow - if not reverse - the increase in inequality. To see how the wealth tax would work, consider a family with $500,000 in wealth and $200,000 in annual income. Right now, they might pay $50,000 in federal income tax. With the wealth tax brackets described above, they would pay nothing. On the other hand, a family with $4 million in wealth and $200,000 in annual income would owe $65,000. Most families that depend on their wealth for their income would pay more, and most that depend on their earnings would pay less. Daniel Altman, an adjunct associate professor of economics at the New York University Stern School of Business and a former member of the New York Times editorial board, is writing a book about what would happen if the United States defaulted on its debts.