If U.S. Rep. John Linder (R-Ga.) has his way, April 15 will no longer be a dreaded day on the calendar; the only Americans paying taxes on that day would be those who go shopping. That's because Mr. Linder wants to replace the current federal income tax system (personal taxes, payroll taxes, corporate taxes, all of it) with a 23 percent national sales tax. The tax would be collected at the point of sale for new goods and services, and it would appear on every retail receipt. Each American would choose how much he pays in taxes by deciding how...