Regardless of what critics say, the U.S. has already had experience with the flat tax concept.

• One-fourth of all states with income taxes have just a single rate.

• A majority of state corporate income taxes impose a single tax rate.

• All sales taxes, including all federal excise taxes, are imposed at a single rate (e.g., no one pays more tax per gallon of gasoline because of his income or the amount of gasoline he consumes).

But an even larger federal flat tax program is Social Security.

• The Social Security payroll tax is a flat 5.6 percent tax rate on both employers and employees on all wages up to $62,700.

• There are no exemptions whatsoever and no taxes at all on income from capital or wages above the maximum.

• Because the payroll tax has no exemptions and does not apply to capital or high wage incomes, it is the simplest of taxes to administer and does not greatly discourage economic activity.

Those who oppose the flat tax because it is not "progressive" in nature would also be the ones to oppose just this aspect of Social Security were it to be introduced today. Flat tax advocates, on the other hand, simply want the income tax to be more like the Social Security tax -- a flat tax that works.

Editorial, "The Very Model of a Modern Flat Tax..." Washington Times, March 4, 1996.