Individuals vary considerably in how much they earn during their lifetimes. This study examines the role of the tax-and-transfer system in mitigating such inequalities, which could otherwise lead to disparities in living standards. Utilizing a life-cycle model, we determine that taxes and transfers offset 45% of lifetime earnings inequality attributed to differences in productive abilities and education. Additionally, the system insures against 48% of lifetime earnings risk. Implementing a lifetime tax reform linking annual taxes to previous employment could improve the system’s insurance capabilities, albeit at the cost of a lower employment rate.