The A-K Model: It's Past, Present, and Future

Almost two decades have passed since the development of the prototype of the Auerbach-Kotlikoff dynamic life-cycle simulation model. The model has been used to examine a host of policies, including tax reform, tax cuts, investment incentives, tax progressivity, expansion of social security, government spending, monetary policy, endogenous growth, the size of the informal sector, human capital accumulation, and educational policy. It has also been used to study demographic change, the timing of policy impacts, the efficiency gains from fiscal reforms, and the effects of fiscal policies on both the intra- and intergenerational distributions of economic welfare. Auerbach and Kotlikoff and their co-authors have done much of this research. The rest has been done by other economists in academia, government, and multilateral lending institutions, many of whom have developed their own versions of the model. This paper describes the origins of the A-K Model, its current structure, the lessons learned using it, and some of the questions that remain to be addressed. It also considers two issues -- tax reform and social security privatization -- in illustrating the model's current capacities.