A few of the candidates for the Republican nomination are proposing a flat tax instead of our current progressive tax.

A progressive tax raises the tax rate as income increases; in other words a wealthy person pays a high percentage of his income in taxes than a poor person. Here are the 2011 tax rates on individuals:

We also tax corporations, but at different levels (I got this from Small Business, Taxes, and Management web page):

OK, so far so good. Now here’s where it gets complicated: there are deductions to income. From the time the government taxed income in 1913, interest on your home mortgage could be deducted from your income. We can also deduct money donated to charities, and lots of other places. Every time the President says: “and I call on Congress to give a tax break to people who…” it creates another deduction. We use tax deductions all the time to change behavior. We deduct mortgage interest rates because we want to encourage people to own homes; we deduct charitable contributions because we want people to donate to places of worship, food banks, and other charities.

We also want people to save money for retirement. If you contribute money to an IRA, a 401(k) or a 403(b), that money isn’t taxed when earned but is taxed years later when withdrawn. It is generally assumed that money will be taxed at a lower rate because income is usually lower in retirement.

This means that the money you earn isn’t the money you pay taxes on. The hard work of determining your taxes isn’t figuring out how much you owe; it’s how your taxable income is determined. The hard part of doing your taxes (and the reason most of us have a professional do our taxes) is finding the difference between your gross income and your taxable income. Once that is calculated we can look on a table to see what we owe.

So here’s the rub: the candidates who propose a flat tax argue that it’s fairer than a progressive tax and will make it easier for all of us to do our taxes. I suspect most taxpayers don’t really know what percentage they pay in taxes but have a sense that it’s too much. But I do think that most people think the tax code is way too complicated and don’t like the fact that they either need to pay a professional or spend hours preparing their tax return. Do these proposals do what they promise? I propose to look at the plans of three of the current Republican candidates: Herman Cain, Ron Paul, and Rick Perry.

Herman Cain: Mr. Cain proposes what he calls his 999 Plan for Economic Renewal. It is elegant in its simplicity: Personal and corporate income are both taxed at 9%, and a 9% federal sales tax is imposed. That means that if you earn $50,000 this year, your tax would be $4,500. If your corporation makes $500,000 it pays $45,000. If you buy $100 in groceries your bill will be $109. Right?

Not exactly. According to his web page, individuals will pay 9% of their gross income minus money donated to charity. Also there will be tax breaks for people who live or work in an Empowerment Zone (though he doesn’t explain what an Empowerment Zone is or how its chosen). This begins the process of determining the difference between gross income and adjusted gross income. I have a hard time imagining that once this door is cracked open Congress won’t want to add deductions.

Shortly after he announced the 999 plan last month he came under criticism for making even the poorest pay the same rate as the richest. Even though this is the basic foundation of a flat tax, Mr. Cain tinkered with his plan. You can read about it on Fox News: he amended his plan to make anyone at or below the poverty level exempt from the 9% tax, now called 909. Here’s an interesting question: if you’re marginally above the poverty rate but donate enough money (or live in an Empowerment Zone) to adjust your income below the poverty rate, does your tax bill drop from 9% to 0%?

Perhaps the most controversial part of this is the 9% sales tax. There is currently no federal sales tax on most things (though there is an 18.4% tax on gasoline). Many states and localities do have a variety of sales taxes. Where I live there is a 7.75% sales tax on most items, but not on groceries. It’s not clear that Mr. Cain’s plan would add 9% to current local sales tax, or if it replaces those taxes, how states and localities would replace that money.

Ron Paul: This is hard to decipher, but you can look for yourself at his page on taxes. Ron suggests eliminating income taxes on individuals (and, interestingly enough, taxes on tips. I guess he figures that if you work in the restaurant or the hospitality industry, tips aren’t income). In any case, Ron is running for the Republican nomination, but he’s really a libertarian. He calls for a Constitutional Amendment that repeals the 16th Amendment and also calls for the closing of the IRS. He doesn’t worry so much about raising the money to fund the government as to shrinking the government to fit within the available funds. Government funds would be raised by a 15% flat rate on corporations.

Rick Perry proposes a hybrid plan. Essentially he gives the taxpayers a choice: pay your taxes under the current tax code, or choose his New Flat Tax System. That system uses a form called the 1040EZR. You put in your gross income, claim $12,500 for each exemption, deduct mortgage interest, charitable contributions, state/local taxes, and capital gains/dividends. This gives you a taxable income and you pay 20% of that. Governor Perry thinks this 1040EZR will be appealing enough that many taxpayers will use this form over the standard 1040 even if their taxes will go up.

So where does this leave us? The idea of a flat tax appeals to the fairness in all of us, but proponents of progressive tax argue that those who have more can bear a larger share. Right now if Bill Gates and I purchase the same car we would pay the same sales tax, but since he makes more money than I do, he would pay more in income tax.

These candidates, and others, argue a flat tax is not only fairer but also easier. The problem, at least with Cain and Perry, is they have already abandoned a pure flat tax to the extent that both allow deductions for charitable contributions. I also wonder about the pushback any candidate would get (for example) from the National Association of Realtors for trying to eliminate the deduction for mortgage interest.