- d. S- 10. Susan, a calendar year taxpayer, lists her principal residence with a realtor on February 7, 2021, enters into a contract to sell on July 12, 2021, and sells (i.e., the closing date) the residence on August 1, 2021. The realized gain on the sale is $225,000. Which date is the appropriate ending date in determining if the residence has been owned and used by the Susan as the principal residence for at least two years during the prior five-year period? a. February 7, 2021. b. July 12, 2021. c. August 1, 2021. d. December 31, 2021.