By David Cay Johnston

The views expressed are his own.

In nearly all 34 countries with modern economies, inequality is rising, a new study by the Organization for Economic Cooperation and Development shows. The gap is especially pronounced in the United States where the country’s largest program to alleviate poverty may be adding to the problem, not alleviating it.

The United States ranks fourth in income inequality after Chile, Mexico and Turkey. In the U.S. the best-off 10 percent make on average 15 times the incomes of the poorest 10th, compared to a six to one ratio in the Nordic countries, Austria, Hungary and Switzerland.

The OECD report, published on Monday, cites the U.S. earned income tax credit as an explanation for a sharp increase in the hours worked by low-wage Americans.

The tax credit, the largest U.S. program to alleviate poverty, is meant to be an incentive to work, but it may also contribute to poverty, effectively holding down wages of all low-skilled workers. Now how is that?

Imagine that more people whose skills limit them to low-paid work decide to work more hours so they can get the credit. Add in people who have the skills for better-paid work but cannot find it and so take lower-paid jobs because of the implicit supplement to their wages provided by the earned income tax credit.