Before revision: Individual level and exhaustive income data for Romania (Cluj county ) is analysed for several consecutive years. The income distributions collapse on a master-curve when a properly normalised income is considered.
After revision: We provide an analytically treatable model that describes in a unified manner income distribution for all income categories. The approach is based on a master equation with growth and reset terms. The model assumptions on the growth and reset rates are tested on an exhaustive database with incomes on individual level spanning a nine year period in the Cluj county (Romania). In agreement with our theoretical predictions we find that income distributions computed for several years collapse on a master-curve when a properly normalised income is considered.