This paper explores the effect of the progressivity of income taxes on the distribution of income and consumption across households as well as the aggregate output in Korea. Using Korean administrative data on income and tax by income percentile,we find that the post-2012 progressivity of Korean income taxes is double the pre-2012 progressivity. By building a dynamic general equilibrium model with heterogeneous agents, we quantify the long-run effect of the increased progressivity of income taxes on Korean economy. We find that the more progressive income taxes increase the government's tax revenue, while reducing the dispersion in income and consumption across individuals. However, the bottom decile of the income distribution is the only group that experiences a rise in consumption, while the consumption of all other income deciles is reduced. This is attributed to the large decline in the aggregate capital. Faced with the increased tax burden, high income earners reduce their savings, causing the aggregate capital and thereby output to decrease.