Christina D. Romer and David H. Romer:
The Incentive Effects of Marginal Tax Rates: Evidence from the Interwar Era: This paper uses the interwar period in the United States as a laboratory for investigating the incentive effects of changes in marginal income tax rates. Marginal rates changed frequently and drastically in the 1920s and 1930s, and the changes varied greatly across income groups at the top of the income distribution. We examine the effect of these changes on taxable income using time-series/cross-section analysis of data on income and taxes by small slices of the income distribution. We find that the elasticity of taxable income to changes in the log after-tax share (one minus the marginal rate) is positive but small (approximately 0.2) and precisely estimated (a t-statistic over 6). The estimate is highly robust. We also examine the time-series response of available indicators of investment and entrepreneurial activity to changes in marginal rates. We find suggestive evidence of an impact on business formation, but no evidence of an important impact on other indicators.
How Much Do Taxes Matter?: The Romers’ elasticity estimate is lower than earlier empirical estimates that are largely based on the postwar period. To put this in perspective, an elasticity of 0.19 implies that tax revenues would be maximized with a tax rate of 84 percent…. Second, remember that this is a study of the super-rich…. These are the people whom one would expect to have the highest income elasticity….
Emmanuel Saez, Joel Slemrod, and Seth H. Giertz conclude in “The Elasticity of Taxable Income with Respect to Marginal Tax Rates: A Critical Review” (pp. 49–50):
while there is compelling U.S. evidence of strong behavioral responses to taxation at the upper end of the distribution around the main tax reform episodes since 1980, in all cases those responses fall in the first two tiers of the Slemrod (1990, 1995) hierarchy—timing and avoidance. In contrast, there is no compelling evidence to date of real economic responses to tax rates (the bottom tier in Slemrod’s hierarchy) at the top of the income distribution.
In other words, recent U.S. history shows that when you raise taxes on the rich, they don’t stop trying to make money: they just pay their lawyers and accountants more to avoid paying taxes. The solution to that is a simpler tax code with fewer exclusions and deductions.