Some former supporters of a flat income tax have turned against it as being politically hopeless, says economist Bruce Bartlett. They treat the failure of Steve Forbes’ candidacy for the presidency as a no vote on the flat tax. They also say a flat tax -- which would apply a single tax rate to all wage income and eliminate the double taxation of capital -- reduces taxes on the wealthy too much compared to middle- and low-income earners.

Steve Moore of the Cato Institute, who once helped Congressman Dick Armey (R-Tex.) develop his flat tax bill, now says, “This is a political non-starter.”

Instead, Moore proposes allowing people to choose a 25 percent flat tax with no deductions, but a credit for Social Security and Medicare payroll taxes. Anyone who wouldn't save taxes with this scheme could simply continue in the existing tax system.

But Bartlett says the point of the flat tax is to get people to stop making investment decisions based on the tax law rather than fundamental economics.

• Moore's "alternative maximum tax" wouldn’t change behavior because no one would be forced to give up economically unjustified deductions, exemptions and exclusions.

• It ignores altogether the corporate side of the tax code, which is where the greatest problems lie.

• And it would preserve the double taxation of capital by including capital gains, dividends and interest in taxable income, while continuing to separately tax corporations.

Bartlett says we need a complete replacement for the tax code, such as the Armey/Forbes plan -- not more gimmicky additions to it.