The time value of an option is primarily derived from future income uncertainty. Empirical results obtained by Quigg (1993), Sing and Patel (2001), and Anthony and Roger (2004) indicate that the ratios of time value to land value are 6-32%. This study empirically estimates the ratio of time value to land value for Tainan residential property transaction data during 2001-2005. Empirical results indicate that the ratio of time value to land value is 11.96% on average, and the ratio of time value to land value decreases over time as land development approaches completion.