中文摘要
本文研究社会保险的扩张如何影响家庭的债务积累。保险可以通过减轻疾病和失业等不利事件的财务影响来减少对债务的依赖。但它也可能削弱通过储蓄进行自我保险的动机，而家庭财务韧性的改善可能增加信贷的可获得性。我们利用1,000万人的数据以及准实验研究设计，利用美国最大社会保险项目之一——医疗补助（Medicaid）——交错扩张在邮政编码层面的暴露异质性，估计保险扩张对家庭债务的因果效应。我们发现，邮政编码内医疗补助合格人口增加1个百分点，信用卡借款增加0.38%。在家庭借款模型中分解这一效应，我们表明，家庭财务韧性改善所引发的信贷供给增加驱动了借款的上升，并贡献了医疗补助扩张净福利收益的30%。
Abstract
This paper investigates how the expansion of social insurance affects households’ accumulation of debt. Insurance can reduce reliance on debt by lessening the financial impact of adverse events such as illness and job loss. But it can also weaken the motive to self-insure through savings, and households’ improved financial resilience can increase access to credit. Using data on 10 million people and a quasi-experimental research design, we estimate the causal effect of expanded insurance on household debt, exploiting ZIP-level heterogeneity in exposure to the staggered expansions of one of the largest US social insurance programs: Medicaid. We find that a 1 percentage point increase in a ZIP code’s Medicaid-eligible population increases credit card borrowing by 0.38%. Decomposing this effect in a model of household borrowing, we show that increased credit supply in response to households’ improved financial resilience drives the rise in borrowing and contributes 30% of the net welfare gains of expanding Medicaid.