The idea of a flat tax — a perennial favorite of some conservatives — is once again getting attention, with three Republican presidential contenders offering hybrid versions of a simplified tax system.

Proponents believe such a tax would spur economic growth, while opponents say it benefits the rich at the expense of the middle class.

“It’s certainly the long-term dream of tax reform,” said David S. Logan, economist at the Tax Foundation, a Washington D.C.-based, non-partisan, tax-policy research organization.

But Logan said none of the candidates are proposing a pure flat tax, “so on some level, they are compromising.”

Texas Gov. Rick Perry rolled out his plan Tuesday, joining Herman Cain and Newt Gingrich, who also offer versions of a flat tax.

“They have a history of trying to protect the millionaires and going after the middle class,” said Mark Owens, chairman of the Montgomery County Democratic Party. “The flat tax is supposedly an easy answer, but it is a regressive tax.”

Supporters of the flat tax say it would lead to economic growth and save the government money by eliminating the cost of enforcing a complicated tax code. Former presidential candidate Steve Forbes, long a proponent of the flat tax, was Perry’s chief advisor on the issue.

Perry would give people a choice of paying a flat tax of 20 percent with a $12,500 standard deduction per person or sticking with the current tax code with its seven rates ranging from 0 to 35 percent depending on income level, said Logan.

The corporate tax would be lowered to 20 percent from the current 35 percent.

Cain’s plan sets a 9 percent flat rate for income taxes, corporate taxes and a new national sales tax. Gingrich calls for an optional 15-percent flat income tax and lowers the corporate rate to 12.5 percent.

Cain would eliminate mortgage deductions, but Gingrich and Perry would keep them, with Perry’s plan limiting them for the highest income levels.

The flat tax in its pure form would levy income taxes at a single rate on everyone, with no deductions or tax credits, and with the elimination of taxes on capital gains and estates.

Its cousin is the “fair tax,” which would eliminate the federal income tax altogether and replace it with a national consumption, or sales, tax.

“In general a flat tax, if it could be implemented in its ideal form, has the possibility of being more efficient, or leading to more economic efficiency for the economy,” said Tom Traynor, professor of economics at Wright State University.

Theoretically it could spur economic growth because companies and individuals would not be held back by fear of moving up a tax bracket if they make more money, said Traynor.

And Logan said the savings and investment provisions, like the elimination of capital gains taxes, could spur growth.

He added, however, that it would help the wealthy more than lower-income people.

“The devil is in the details on these things,” said Traynor.

To generate the same amount of revenue as the current system, the flat tax would have to be set at a percentage higher than most people now pay, Traynor said.

“Probably 80 percent of the population would see an increase in the percentage of the income they pay in taxes,” he said.

Many conservatives argue that spending cuts would reduce the need to keep revenue stable.

Ben LaBolt, a campaign spokesman for President Barack Obama, blasted the flat-tax plans, as well as the tax proposals of Republican candidate Mitt Romney, who says he would lower the corporate tax to 25 percent.

“The belief that middle-class Americans will benefit if we just give another special break to those at the top was long ago discredited,” said LaBolt.

Greg Gantt, chairman of the Montgomery County Republican Party, said he supports tax reform, but believes it should be done in smaller increments.

“These huge overhauls seem to be not doing well with the public,” he said. “So then we just sit and nothing happens.”

Support for the flat tax has typically run aground on deductions, said Steve Ellis, vice president of Taxpayers for Common Sense, a Washington, D.C., non-partisan budget watchdog.

“It’s something people feel like must be in the Constitution or something: that you deduct your mortgage,” he said.

Many people conceptually like the idea of a nice, simple system, Ellis said. They also like deductions for their kids, college costs, state income or sales taxes, charitable contributions and child care, he said.

And there is concern that employee health care will be cut if corporations lose the generous federal tax credit for providing that benefit, Ellis said.

Simple systems don’t always stay that way. Economists said the federal tax code has become increasingly complex since its last major reform in 1986.

“Congress loves to use the tax code to target a subsidy to this group of people and this other group of people,” said Ellis. “If you create rules, people are going to find ways to get around them and use them to their advantage.”

Contact this reporter at (937) 225-7455 or lhulsey@DaytonDailyNews.com.