







This paper examines how the precautionary motive varies with income. I first develop a theoretical benchmark of how we would expect precaution to vary with income starting from a basic version of the buffer-stock model. Emergency savings provide a way for households to smooth over shocks and so give insight into the precautionary motive. Using data from the Survey of Consumer Finances in the USA, I show that as income declines, the desired emergency savings relative to income increase, suggesting that low-income households are more precautionary. Observable differences, such as income uncertainty, do not explain the rise. Instead, I propose and estimate a model with a minimum subsistence level and unexpected expenses. The model implies that low-income households are increasingly exposed to shocks, explaining the increase in precaution. Supporting the approach, I show that expenses on repairs are a larger fraction of the spending of low-income households.
What Would You Do with $500? Spending Responses to Gains, Losses, News, and Loans
Abstract We use survey questions about spending in hypothetical scenarios to investigate features of propensities to consume that are useful for distinguishing between consumption theories. We find that (1) responses to unanticipated gains are vastly heterogeneous (either zero or substantially positive); (2) responses increase in the size of the gain, driven by the extensive margin of spending adjustments; (3) responses to losses are much larger and more widespread than responses to gains; and (4) even those with large responses to gains do not respond to news about future gains. These four findings suggest that limited access to disposable resources, and frictions in adjusting consumption, are important determinants of consumption behaviour. We also find that (5) households do not respond to the offer of a one-year interest-free loan, suggesting that this is not a consequence of short-term credit constraints; and (6) people do cut spending in response to news about future losses, suggesting that neither is this a consequence of myopia. A calibrated precautionary savings model with utility costs of changing consumption, and a sufficient fraction of low-wealth households, can account for these features of propensities to consume on both the extensive and intensive margins.

A Theory of the Consumption Function, with and without Liquidity Constraints
This paper argues that the modern stochastic consumption model, in which impatient consumers face uninsurable labor income risk, matches Milton Friedman's (1957) original description of the Permanent Income Hypothesis much better than the perfect foresight or certainty equivalent models did. The model can explain the high marginal propensity to consume, the high discount rate on future income, and the important role for precautionary behavior that were all part of Friedman's original framework. The paper also explains the relationship of these questions to the Euler equation literature, and argues that the effects of precautionary saving and liquidity constraints are often virtually indistinguishable.
Credit Crises, Precautionary Savings, and the Liquidity Trap*
Abstract We study the effects of a credit crunch on consumer spending in a heterogeneous-agent incomplete-market model. After an unexpected permanent tightening in consumers’ borrowing capacity, constrained consumers are forced to repay their debt, and unconstrained consumers increase their precautionary savings. This depresses interest rates, especially in the short run, and generates an output drop, even with flexible prices. The output drop is larger with sticky prices, if the zero lower bound prevents the interest rate from adjusting downward. Adding durable goods to the model, households take larger debt positions and the output response can be larger.

Consumption and Debt Response to Unanticipated Income Shocks: Evidence from a Natural Experiment in Singapore
This paper uses a unique panel dataset of consumer financial transactions to study how consumers respond to an exogenous unanticipated income shock. Consumption rose significantly after the fiscal policy announcement: during the ten subsequent months, for each $1 received, consumers on average spent $0.80. We find a strong announcement effect—19 percent of the response occurs during the first two-month announcement period via credit cards. Subsequently, consumers switched to debit cards after disbursement before finally increasing spending on credit cards in the later months. Consumers with low liquid assets or with low credit card limit experienced stronger consumption responses. (JEL D12, D14, E21)
Rules of Thumb in Household Savings Decisions: Estimation Using Threshold Regression
The rules of thumb offered by financial advisors regarding how much to hold in liquid reserves vary widely and usually imply far greater sums than low-income ho
Consumer Spending during Unemployment: Positive and Normative Implications
Using de-identified bank account data, we show that spending drops sharply at the large and predictable decrease in income arising from the exhaustion of unemployment insurance (UI) benefits. We use the high-frequency response to a predictable income decline as a new test to distinguish between alternative consumption models. The sensitivity of spending to income we document is inconsistent with rational models of liquidity-constrained households, but is consistent with behavioral models with present-biased or myopic households. Depressed spending after exhaustion also implies that the consumption-smoothing gains from extending UI benefits are four times larger than from raising UI benefit levels. (JEL D14, D91, E21, E24, E70, J65)
A Debt Puzzle
Over 60% of US households with credit cards are currently borrowing – i.e., paying interest – on those cards. We attempt to reconcile the high rate of credit card borrowing with observed levels of life cycle wealth accumulation. We simulate a lifecycle model with five properties that create demand for credit card borrowing. First, the calibrated labor income path slopes upward early in life. Second, income has transitory shocks. Third, consumers invest actively in an illiquid asset, which is sufficiently illiquid that it can not be used to smooth transitory income shocks. Fourth, consumers may declare bankruptcy, reducing the effective cost of credit card borrowing. Fifth, households have relatively more dependents early in the life-cycle. Our calibrated model predicts that 20% of the population will borrow on their credit card at any point in time, far less than the observed rate of over 60%. We identify a resolution to this puzzle: hyperbolic time preferences. Simulated hyperbolic consumers borrow actively in the revolving credit card market and accumulate relatively large stocks of illiquid wealth, matching observed data.

Knowing When to Spend: Unintended Financial Consequences of Earmarking to Encourage Savings
Maintaining savings is an important financial goal. Yet there are times when savings should be spent, such as when people face unavoidable costs, and spending their savings allows them to avoid high interest rate debt. Existing behavioral research has focused on consumer decisions between savings and discretionary spending and has proposed interventions to promote savings in these contexts. However, when spending is not discretionary, such interventions could risk exacerbating a pattern found in economic research in which people borrow high interest rate debt while maintaining savings that earn low levels of interest. To examine how mental accounting interacts with considerations of personal responsibility and guilt to contribute to this pattern, this article explores whether people spend their savings when they need money most: during emergencies. Six studies reveal that people's tendency to preserve savings by borrowing from a high interest rate credit option varies as a function of the savings’ intended use. Paradoxically, people are most likely to turn to high interest rate credit with the belief that doing so is the responsible option.

The Self-Constrained Hand-to-Mouth
Abstract Many studies have shown that consumption responds to the arrival of predictable income (excess sensitivity). This paper uses a buffer stock model of consumption to understand what causes excess sensitivity and to test which parameterization is consistent with empirical excess sensitivity estimates. Using high-frequency granular data from a personal finance app, I find that while liquidity constraints are a proximate cause, preferences are the ultimate cause of excess sensitivity. Furthermore, it finds that for feasible parameters, a quasi-hyperbolic version of the model is more consistent with the level of excess sensitivity relative to a standard exponential model.

Consumption Response to Credit Expansions: Evidence from Experimental Assignment of 45,307 Credit Lines
In a field experiment that constructs a randomized credit limit shock, participants borrow to spend 11 cents on the dollar in the first quarter and 28 cents by the third year. Effects extend to those far from the limit, those who had the new limits as available credit, and those with a liquid asset buffer. In the short-run, flexible and installment contracts are used in tandem, with unconstrained using installments more. Long-run borrowing is predominantly using installments. Near limits, participants borrow when credit expands but save out of constraints when limits are tight. Findings support a buffer-stock interpretation emphasizing precautionary saving.
Household Debt: Facts, Puzzles, Theories, and Policies
Borrowing decisions affect most households, with large stakes and implications for research subfields as varied as macroeconomics and industrial organization. I review theoretical and empirical work on household debt: its prevalence, level, growth, and composition, as well as various measures of consumer choice and market (in)efficiency, elasticities, and prices, including new evidence on how borrowing heterogeneity affects the distribution of the opportunity cost of consumption. I also discuss opportunities and challenges in policy evaluation. A key takeaway is that puzzles abound, and I highlight numerous avenues for further research.

Liquidity versus Wealth in Household Debt Obligations: Evidence from Housing Policy in the Great Recession
We exploit variation in mortgage modifications to disentangle the impact of reducing long-term obligations with no change in short-term payments ("wealth"), and reducing short-term payments with no change in long-term obligations ("liquidity"). Using regression discontinuity and difference-in-differences research designs with administrative data measuring default and consumption, we find that principal reductions that increase wealth without affecting liquidity have no effect, while maturity extensions that increase only liquidity have large effects. This suggests that liquidity drives default and consumption decisions for borrowers in our sample and that distressed debt restructurings can be redesigned with substantial gains to borrowers, lenders, and taxpayers.
How Are SNAP Benefits Spent? Evidence from a Retail Panel
We use a novel retail panel with detailed transaction records to study the effect of the Supplemental Nutrition Assistance Program (SNAP) on house-hold spending. We use administrative data to motivate three approaches to causal inference. The marginal propensity to consume SNAP-eligible food (MPCF) out of SNAP benefits is 0.5 to 0.6. The MPCF out of cash is much smaller. These patterns obtain even for households for whom SNAP benefits are economically equivalent to cash because their benefits are below their food spending. Using a semiparametric framework, we reject the hypothesis that households respect the fungibility of money. A model with mental accounting can match the facts.
Cash versus Debit Card: The Role of Budget Control
Due to the financial crisis, an increasing number of households face financial problems. This may lead to an increasing need for monitoring spending and budgets. We demonstrate that both cash and the debit card are perceived as helpful in this respect. We show that, on average, consumers responsible for financial decision making within a household find cash and the debit card equally helpful for monitoring their household finances. Individuals differ in major respects, however. In particular, low earners and the liquidity‐constrained prefer cash as a budgeting tool. Finally, we present evidence that at an aggregated level, such preferences strongly affect consumer payment behavior. These findings suggest that the substitution of cash by cards may slow down because of the financial crisis.

Beyond Income: Dynamic Consumer Financial Vulnerability
This research challenges the entrenched belief that financial vulnerability affects only low-income consumers. Instead, most consumers across the socioeconomic spectrum experience varying degrees of financial vulnerability at different points during their lives, whether sporadically or chronically; vulnerability is dynamic and heterogeneous. The authors propose a novel, theory-driven definition of consumer financial vulnerability (CFV) as the risk of incurring future harm, given the consumer's current access to various financial resources. A new conceptual framework decouples “vulnerability” from “harm” to distinguish the state of CFV, its determinants (access to various interdependent financial resources), and the constructs it foreshadows (multiple interconnected forms of realized harm). Five research propositions follow: (1) financial resource volatility plays a vital role in CFV, (2) recovering from harm requires more financial resources than preventing harm, (3) a multiperiod lens is needed to assess CFV accurately, (4) greater financial resource access can increase CFV, and (5) generalized financial literacy is not a panacea for mitigating CFV. The propositions and their implications for marketing strategy, public policy, and consumer well-being offer a rich research agenda. The authors propose a measure of CFV—the probability that financial resources are insufficient to meet or exceed a harm threshold—for future empirical investigations.

The Coholding Puzzle: New Evidence from Transaction-Level Data
Abstract Why do individuals pay debt interest when they could use their savings to pay down the debt? We explore why individuals “cohold” debt and savings using detailed and highly disaggregated daily-level data on household finances. We find that coholding mostly occurs in short spells within the month and the level of coholding is typically modest. Periods of coholding are not associated with shocks at the individual level. We show that mental accounting has a role to play in explaining coholding, in particular how individuals allocate different categories of expenditure to accounts in credit and debit.
