Introduction

The provision of long-term policy advice requires projections of government debt. Models have been widely produced to generate expenditures and tax revenues on the assumption that various age-specific rates and fiscal policy variables remain unchanged. As a result of population ageing, current policy settings in many countries lead to unsustainable levels of public debt. The present book is motivated by two limitations of the standard models. First, they seldom contain feedback effects arising from endogenous responses on the part of individuals and policy-makers. Second, the models seldom make an allowance for uncertainty, which creates the problem of whether, in the face of anticipated debt increases, tax rates should be increased earlier rather than delaying, and if so by how much? This book presents new modelling approaches to allow for feedbacks and uncertainty, and to analyse optimal policy. The modelling innovations can be applied to any country, but for illustrative purposes they are calibrated to examine the case of New Zealand.