We compare the twelve-month default probability among subprime borrowers differing only in the number of months before their first lump-sum property tax payment, after which time they may be exposed to reduced liquidity. We show that borrowers with an earlier property tax bill—within three months of origination—have 2% to 6% higher first-year default rates than borrowers facing their first property tax bill ten to twelve months after origination. Lump-sum property tax payments appear to produce a persistent state of low liquidity, the length of which raises the likelihood of default. These results are about one-third the effect size of a transition from 10% positive to 20% negative equity found in the literature. This paper provides causal evidence that liquidity constraints are important predictors of mortgage default.

ABSTRACT From 2007 to 2009 U.S. house prices plunged and mortgage defaults surged. While ostensibly consistent with widespread “ruthless default,” analysis of detailed mortgage and house price data indicates that borrowers do not walk away until they are deeply underwater—far deeper than traditional models predict. The evidence suggests that lender recourse is not the major driver of this result. We argue that emotional and behavioral factors play an important role in decisions to continue paying. Borrower reluctance to walk away implies that the moral hazard cost of default as a form of social insurance may be lower than suspected.