Here’s issue #8 of my Policy and Politics Newsletter, written 12/1/11 . Having reviewed historical income tax rates in the last newsletter, this one will take a look at the flat tax, which is being proposed by a number of the Republican presidential candidates.
The flat tax – a simplified federal income tax with one tax rate for everyone – is a favorite tax reform of many of the Republican presidential candidates. It is almost always designed to be a “revenue neutral” option to the current, more complicated income tax, meaning that it would raise the same amount of revenue for the federal government as the current tax.
To produce the same amount of revenue, the flat rate has to be somewhere in the middle between the highest rate (now 35%) and the lowest rate (now 10%). Because the flat rate is lower than the current rates for high income filers, high income people would pay less. As a result, to be revenue neutral, middle and low income people will have to pay more. 
Some of the Republican presidential candidates have proposed variations on the flat tax to ensure that no one would pay more income tax than they do currently or to reduce the negative impact on low and middle income filers. Because these variations would reduce the total revenue to the federal government, they would not be revenue neutral and would increase the federal deficit substantially.
For example, under candidate Herman Cain’s 9-9-9 plan, the flat income tax rate of 9% is lower than all the current rates. (Note that the lowest income filers actually currently pay no income tax because of the personal exemption [$3,650 per person] and the Earned Income Tax Credit.) To make the overall plan revenue neutral, he proposes a 9% national sales tax that would apply to all purchases, including food and clothing. As a result, it is estimated that the highest income 1% of filers would pay $210,000 less in taxes and the lowest income 60% of filers would pay on average $2,000 more.  (Note candidate Cain has since said that his plan would include a provision to ensure that those with the very lowest incomes wouldn’t pay more.)
The flat tax is often promoted as being “fair,” because everyone pays the same rate. However, many people believe “fair” means a graduated or progressive income tax, where people with higher incomes pay a higher percentage of their income because they can afford it, as a smaller portion of their income is needed to pay for basic living expenses. In other words, higher income people have more discretionary income and therefore can afford to pay more in taxes. This is the concept behind our graduated federal income tax system and has been since the income tax was first implemented in 1913. If you believe a graduated income tax is “fair,” then the flat tax, by definition, is not “fair.”  And as you know from the previous newsletter, today’s income tax rates are less progressive than they used to be: today’s highest rate for the highest income filers is 35%, while in 1980 it was 72% and in 1950s and early 1960s it was 91%.
 Reischauer, Robert, former Director of the Congressional Budget Office as quoted in Scott Leigh, 10/28/11, “Flat-tax fantasies – and the realities,” The Boston Globe.
 Citizens for Tax Justice as cited in Jay Fitzgerald, Boston Globe article, 10/30/11, “Flat tax, fat cats, and you.”
 Leigh, Scott, 10/28/11, “Flat-tax fantasies – and the realities,” The Boston Globe.