Emmanuel Saez, E. Morris Cox professor of economics, University of California at Berkeley:
"The tax rate t maximizing revenue is: t=1/(1+a*e) where a is the Pareto parameter of the income distribution (= 1.5 in the U.S. and easy to measure), and e the elasticity of reported income with respect to 1-t which captures supply side effects. The most reasonable estimates for e vary from 0.12 to 0.40 (see conclusion page 47) so e=.25 seems like a reasonable estimate. Then t=1/(1+1.5*0.25)=73% which means a top federal income tax rate of 69% (when taking into account the extra tax rates created by Medicare payroll taxes, state income tax rates, and sales taxes) much higher than the current 35% or 39.6% currently discussed."
Joel Slemrod, Paul W. McCracken Collegiate Professor of Business Economics and Public Policy, University of Michigan:
"I would venture that the answer is 60% or higher.... The idea that we're on the wrong side has almost no support among academics who have looked at this. Evidence doesn't suggest we're anywhere near the other end of the Laffer curve.... The elasticity of response, which is the key parameter here, isn't some absolute parameter that we just have to deal with. It depends on policies. Let me be specific. There's an article about how the IRS has reorganized itself to crack down on tax evasion of high-income people and corporations moving their operations or assets offshore. That's the kind of policy initiative that can affect the elasticity of response by closing up a loophole. You want to raise tax rates at the same time you look at these kind of initiatives.... If we're talking about just deficit variations, we're not talking about what the government spending, the answer is no. It doesn't matter what this response is. If you're not changing government spending, any change in revenue now will have to offset by some change in revenue in the future. If that's the case, then if the responsiveness is high now, it's going to be high later, too."