Since the "long run" is not defined, some commentators  have suggested that 20 years should be used, making the annual best case GDP growth equal to 0.
They are also on a 1-for-1 basis. John Maynard Keynesthe founder of Keynesianismsummarized Say's law as "supply creates its own demand".
Of course, this economic history alone does not settle the question of whether there are causal links between top tax rates and economic growth. An increase in marginal tax rates shrinks the tax base, both by discouraging work effort and by encouraging tax avoidance and even tax evasion.
One way to check the long-run elasticity of labor supply is to compare countries, such as France, that have had high marginal tax rates on even middle-income people for a long time with countries, such as the United States, where the marginal rates have been persistently lower.
Now the government cuts tax rates by one-third, from 75 percent to 50 percent. These empirical findings carry an important lesson for our tax policy: Rather than increasing inequality by throwing away revenue on tax cuts for the rich, we should ensure that middle- and lower-income Americans have enough after-tax income to maintain strong consumption levels, especially during economic downturns.
With the reduction in rates in the twenties, higher-income taxpayers reduced their sheltering of income and the number of returns and share of income taxes paid by higher-income taxpayers rose".
Even though economists still disagree about the size and nature of taxpayer response to rate changes, most economists now believe that changes in marginal tax rates exert supply-side effects on the economy. The percentage increases in the real tax revenue collected from the top 1 and top 5 percent of taxpayers were even larger.
Whereas GDP grew at an average annual rate of 3. If Russians with even modest earnings complied with the law, the tax collector took well over half of their incremental income. That helped boost the economy out of the worst recession since the Great Depression.