Lifetime Uncertainty

Lifetime uncertainty represents an additional risk that affects intertemporal choice, because consumers may live longer than expected and run the risk of exhausting the resources accumulated for retirement. Lifetime uncertainty introduces an incentive to consume earlier in life because consumers discount future utility at a higher rate. Second, since in each period there is some positive probability that the consumer will not survive to the next period, the terminal condition on wealth corresponds effectively to a liquidity constraint. Third, with lifetime uncertainty, the decumulation of wealth by the elderly is slower than predicted by the life-cycle model. Finally, the model with lifetime uncertainty generates transfers of wealth across generations even without an express bequest motive, through what we can term involuntary or accidental bequests. The chapter highlights the necessity of accounting for lifetime uncertainty when interpreting empirical age-wealth profiles estimated from microeconomic data.