One of my frustrating missions in life is to educate policy makers on the Laffer Curve.
This means teaching folks on the left that tax policy affects incentives to earn and report taxable income. As such, I try to explain, this means it is wrong to assume a simplistic linear relationship between tax rates and tax revenue. If you double tax rates, for instance, you won't double tax revenue.
But it also means teaching folks on the right that it is wildly wrong to claim that "all tax cuts pay for themselves" or that "tax increases always mean less revenue." Those results occur in rare circumstances, but the real lesson of the Laffer Curve is that some types of tax policy changes will result in changes to taxable income, and those shifts in taxable income will partially offset the impact of changes in tax rates.
If you explain to a conservative politician that a goofy tax cut (such as a new loophole to help housing) won't boost the economy and that the static revenue estimate from the bureaucrats at the Joint Committee on Taxation is probably right, they usually understand.
But liberal politicians get very agitated if you tell them that higher marginal tax rates on investors, entrepreneurs, and small business owners probably won't generate much tax revenue because of incentives (and ability) to reduce taxable income.
To be fair, though, some folks on the left are open to real-world evidence. And this IRS data from the 1980s is particularly effective at helping them understand the high cost of class-warfare taxation (click to enlarge).
There's lots of data here, but pay close attention to the columns on the right and see how much income tax was collected from the rich in 1980, when the top tax rate was 70 percent, and how much was collected from the rich in 1988, when the top tax rate was 28 percent.