The primary motivation of this dissertation is to provide insights into the future developments of mortality and population health, and the associated effects on public finance in the United States. Chapter 2 models the future developments of population health and quantifies the degree of uncertainty in the future developments. Chapter 3 jointly models the future developments of mortality and health, using a similar approach as for health in Chapter 2. This allows us to further investigate the association between the developments of life expectancy and healthy life expectancy, taking into account dependence between developments of mortality and health. Chapter 4 extends the forecast model developed in Chapter 3 by taking into account the dependence between male and female mortality and health. The model is used to estimate the effects on (healthy) life expectancy of a policy that links the retirement age to life expectancy. Finally, Chapter 5 studies another important part of public finance, the growth of healthcare expenditure. In this chapter, we investigate the dynamic relationship between the growth of healthcare cost and a relatively large set of its determinants, with special attention on the effect of people’s health on the growing healthcare cost.