Recent data shows South Korea’s highest income tax rate is above the OECD average.

In a recent report, the Korea Economic Research Institute(KERI) said since the global financial crisis in 2008, the South Korean government has continuously levied higher taxes on high-income earners.

KERI said the highest income tax rate, in particular, was raised from 35 percent in 2012 to 38 percent, which is greater than the average for the Organization for Economic Cooperation and Development(OECD).

The institute said the effective income tax rate applied to those earning an annual income of 300 million won or more is seven times higher than the rate applied to those earning less than the amount.

The think tank pointed out that if the government additionally raises the tax rate on those in the highest income bracket, it will excessively increase their tax burden.

Researcher Lim Dong-won, who authored the report, said that streamlining existing tax exemption or deduction policies instead, will be more effective in order to secure tax revenues.

He cited 48 percent of the country’s working population are exempt from paying income tax and less than 70 percent of small business owners are subject to paying taxes.

The report came as the three main opposition parties have been calling for a further rise in the tax rate for high-income earners.