Focus on families
Concern about income inequality is rising among policymakers, with Federal Reserve Chair Janet Yellen warning in October that it was near its highest level in a century in the U.S.
Globally, the issue was named as the biggest risk for 2015—trumping unemployment—in a survey by the World Economic Forum published last month.
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The OECD said its findings challenged the conservative view that there is a trade-off between promoting growth and addressing inequality.
"Policies that help to limit or reverse inequality may not only make societies less unfair, but also wealthier," it said.
The organization advocated increasing access to education and healthcare, as well as cash transfers to the some of the world's poorest, to tackle the problem.
"Redistribution efforts should focus on families with children and youth, as this is where key decisions on human capital investment are made and should promote skills development and learning across people's lives," the OECD said.
In October, Credit Suisse named Russia as the most economically unequal country in the world, followed by Turkey and Hong Kong. The U.S. also came in relatively high, in seventh place out of all countries.