As April 15 arrives, millions of Americans greet this black-letter date as cheerfully as school kids lining up for vaccine injections. Once again, this will hurt. President Bush’s bipartisan tax-reform commission should endorse a powerfully simple idea that would ease the pain of many taxpayers: Let Americans choose between today’s tax system and a 19-percent flat tax. For now, Americans contend with a federal tax code that has grown luxuriant after ten years of Republican congressional dominance. As Cato Institute tax analyst Chris Edwards reports, federal tax rules that filled 40,500 pages in 1995 stretch to 60,044 pages today. A...