Americans businesses were turned into April Fools on Sunday when a cut in Japan’s top corporate income tax rate left the United States with the highest such rate in the developed world — including Communist China’s. With Great Britain also slicing rates this month from 26 percent to 24 percent, the U.S. average top rate (federal and state combined) of 39.2 percent stands as a tremendous barrier to economic growth, higher incomes and job creation.

Faced with evidence of the ill effects of these high American rates, even Bill Clinton and Barack Obama have paid lip service to cutting them. Yet they and others propose merely to nibble at the edges, from 35 percent to 28 percent. This isn’t enough. There are good reasons to cut it at least in half, or perhaps to the 12.5 percent level that helped create the “Celtic Tiger” of unprecedented economic growth in Ireland.