Top wage incomes in Japan, 1951-2005

Using wage income tax statistics, we construct continuous series of upper wage income shares in Japan from 1951 to 2005 to document the evolution of top wage incomes and investigate their long-run determinants. We find that, while the middle wage income class gained enormously both in absolute and relative terms during the period of high economic growth, the upper wage income class faired comparatively better after 1975. In particular, the shares of total wage accruing to the top 1% wage earners and above have risen steadily since the late 1990s. A simple time-series regression analysis indicates that marginal income tax rates, corporate performance, female labor force participation, and labor disputes are important determinants of top wage income shares in post-WWII Japan. Although not conclusive, our results suggest that much of the recent gains in wage income shares at the top can be explained by the changes in these four factors, placing a less emphasis on a story of structural change.