This paper examines the effect of real estate price decline and interest rate fluctuation on the default risk of mortgage-holding homeowners. Default risk is measured using cash flows and net asset holdings at the household level. First, using a stress test, we examine how these measures are affected by a variety of stress scenarios. The result shows that 0.14%–4.02% of households are at risk of default; therefore, the households’ default risk is not high. However, youth and middle-aged individuals are exposed to higher default risk than other age groups, and an estimated 56.5% of youth exposed to default risk belong to the middle-income class. Second, employing the probit model, we find that socio-demographic characteristics such as sex, age, and education variables are no longer significant independent variables for youth and middle-aged individuals compared with all other age groups. Furthermore, households with low financial assets, low net assets, multiple mortgages, and multiple properties have a higher default risk. Our results shed light on the necessity of monitoring youth and middle-aged individuals' financial health in order to lessen their social and economic impact.