Previous studies of consumer debt risk estimate low sensitivities to negative shocks, contradicting the historical data. This work proposes a heterogeneous agents model of household finances and credit risk. Families suffer labor income shocks and choose from a menu of loans contracts, defaulting on debt commitments when unable to finance minimum consumption standards. Using a variety of survey data I simulate household credit default for Chile over the last 20 years, replicating successfully the highs and lows of consumer delinquency. Some households are shown to be highly vulnerable to changes in interest rates, credit maturities and liquidity.