Optimal chonsei to monthly rent conversion choice given borrowing constraints

Chonsei, an exceptional but prevalent housing rental system in the Republic of Korea, functions as private loans between individuals, and its implicit interest rate is called the “chonsei to monthly rent conversion rate”. Although the chonsei to monthly rent conversion rate is much higher than the interest rate of savings accounts or mortgage loans, making chonsei a more expensive channel of financing, chonsei remains a dominant type of rent in Korea. This study provides a novel theoretical model in a continuous-time portfolio selection framework that allows a lessor, given borrowing constraints, to optimally choose between chonsei and monthly rent contracts to show a possible solution to this situation. We investigate the optimal choice between chonsei and the monthly rent of lessors using a rigorous theoretical model and find a closed-form solution to the model. We analyze how credit availability in the banking sector affects the choice problem, showing that the lessor may prefer the chonsei contract over the monthly rent contract, given the borrowing limit from a bank. In addition, we analyze the impact of other major factors, such as the market price of risk, the amount of chonsei deposit, the monthly rental rate, and the income rate, on the lessor's optimal decision between chonsei and monthly rent.