Intra-generational inequalities focus on the distributions within age groups. On the basis of French household income surveys carried out from 1996 to 2014, the Gini coefficient and D9/D1 inter-decile ratio were calculated so as to evaluate intra-generational income inequality before and after redistribution by the tax and welfare system. Age-Cohort-Period models were then estimated in order to disentangle age and generation effects. Over a life cycle, intra-generational inequality displays a hump-shaped curve peaking at age 55–59. This inequality is significantly lower among the youngest, whichever inequality indicator is used, and among the oldest, when measured by the inter-decile ratio. Comparison of pre- and post-redistribution income reveals that the tax and welfare system particularly reduces inequality among the young. Intra-generational inequality measured by the Gini coefficient increases significantly from one generation to the next. Measured by the inter-decile ratio, the increase is considerable for the gross income of those generations born from the 1970s on. However, the tax and welfare system has compensated for this increase, because analysis of the inter-decile ratio applied to disposable income shows no significant difference between generations.