We study reforms of the social security system within a life cycle model of savings and discretized labor supply. We extend the standard estimation approach that only relies on data moments of life cycle profiles by exploiting quasi-exogenous variation. We explore the importance of such exogenous variation for the estimated parameters and counterfactual policy analyses. Our estimation relies on administrative data from the Netherlands, which actively taxes wealth. Thus, the data used for estimation has minor measurement errors, especially in wealth.