“Personal income tax has risen in 25 out of 34 OECD countries over the past three years, as countries reduce the value of tax-free allowances and tax credits and subject higher proportions of earnings to tax, according to new data in the annual Taxing Wages publication. The increases in tax burdens on labour income in 2013 were largest in Portugal (due to higher statutory rates), the Slovak Republic (due to higher employer social security contributions) and the United States (due to expiry of previous reductions in employee social security contributions). The average tax burden on employment incomes across the OECD increased by 0.2 of a percentage point in 2013, to 35.9 percent, according to the report. It increased in 21 out of 34 countries, fell in 12, and remained unchanged in one. The 2013 rise follows a substantial increase in 2011 and a smaller one in 2012. Since 2010, the tax burden has increased in 21 OECD countries and fallen in 9, partially reversing the reductions seen between 2007 and 2010. The new findings on income tax burdens are among the highlights of Taxing Wages 2014, which provides unique cross-country comparative data on income tax paid by employees as well as the associated social security contributions made by employees and employers; both are key factors when individuals consider their employment options and businesses make hiring decisions. A special chapter of the report assesses how progressivity of tax systems in OECD countries – the role income taxes play to achieve a more equal distribution of income after tax than before – has changed since 2000. he design and interaction of personal income tax systems, social security contributions and benefit systems is shown to have become more progressive for low-income households across the OECD, particularly since the global economic crisis began in 2007, and notably for poorer households with children. This is principally attributed to growth in targeted tax credits or “make-work-pay” provisions for low-income workers, as well as increased child benefits for low-income households. “