Abstract
Income inequality, especially the generational gap of income and ＂generational justice＂ has become a hot topic for the public in Taiwan. However, the determinants of income variety among cohorts are a mixture of economic cycle, life course, education, social class, etc. The mixture also includes multiple factors about time, that is, the age-period-cohort (APC) effects in demographic studies. Many longitudinal surveys are unable to investigate the generational gap because the interviewees are limited in the same birth cohort. By applying the APC model to long-term datasets pooled from different waves of surveys, we estimate the trends of income from different cohorts, age groups and periods in Taiwan. Second, we pooled the Survey of Family Income and Expenditure to estimate the generational difference of personal income between 1990 and 2020 in Taiwan. The empirical evidence demonstrated the same patterns of personal income differences: (1) in contrast with increasing return of graduate school, the income return of university is shrinking; meanwhile, the income differences among employers, the self-employed, skilled workers (new middle classes), and unskilled workers has been amplified in the past three decades. (2) the income gap between the baby boomers and millennials has continued and implies a persistent generational inequality. Finally, each survey has its own advantages and limitations due to the questionnaires and research designs.