A Model of Expenditure Shocks

We document four features of consumption and income microdata: (1) household-level consumption is as volatile as household income on average, (2) household-level consumption has a positive but small correlation with income, (3) many low-wealth households have marginal propensities to consume near zero, and (4) lagged high expenditure is associated with low contemporaneous spending propensities. Our interpretation is that household expenditure depends on time-varying consumption thresholds where marginal utility discontinuously increases. Our model with consumption thresholds matches the four facts better than does a standard model. Poor households in our model also exhibit “excess sensitivity” to anticipated income declines.