A new study from the Cato Institute's Alan Reynolds argues that income inequality is exaggerated:
Tax changes induced thousands of businesses to switch from filing under the corporate tax system to filing under the individual tax system. Corporate executives switched from accepting stock options taxed as capital gains to nonqualified stock options taxed as salaries. The huge growth in tax-favored savings plans, such as 401(k)s, has resulted in billions of dollars of investment income disappearing from tax returns. Meanwhile, studies of inequality that are based on tax return data usually exclude transfer payments, which results in exaggerating the shares of income received by those at the top by ignoring growing amounts of income at the bottom.
In sum, studies based on tax return data provide highly misleading comparisons of changes to the U.S. income distribution because of dramatic changes in tax rules and tax reporting in recent decades. Aside from stock option windfalls during the late-1990s stock-market boom, there is little evidence of a significant or sustained increase in the inequality of U.S. incomes, wages, consumption, or wealth over the past 20 years.
Of course, there's also the question of whether income inequality is really something we ought to worry about , anyway.