1. The judgment of the court of first instance is modified as follows.

The defendant shall pay to the plaintiff KRW 31,518,660 on February 17, 2017.

1. The grounds for this part of the underlying facts are as follows, and except for adding evidence Nos. 9 and 10 to the grounds for recognition Gap, the reasoning of the judgment of the first instance is as stated in Paragraph 1 of the same Article, and this part is cited in accordance with the main sentence of Article 420 of the Civil Procedure Act.

“E. On January 7, 2017, the Plaintiff notified of the decision to revise the capital gains tax, imposing the amount equivalent to the refund money of this case erroneously paid to the Defendant, was served on the Defendant on February 16, 2017.”

2. According to the above facts of recognition, the plaintiff deposited the refund money of this case pursuant to Article 248(1) of the Civil Execution Act, and thus the defendant's claim for the refund money of this case extinguished, and the plaintiff exempted the defendant from the obligation to pay the refund money of this case.

Nevertheless, the defendant, without any legal ground, gains profits by holding the amount equivalent to the refund amount of this case paid from the plaintiff. Thus, the defendant is obligated to return the refund amount of this case and its delay damages to the plaintiff as unjust enrichment.

(1) The Plaintiff’s gross negligence and the Plaintiff’s claim cannot be satisfied because there is no cause attributable to the Defendant. However, the Defendant’s obligation to return unjust enrichment arises due to the extinguishment of legal cause attributable to the Defendant to receive the instant refund, and is irrelevant to the existence of the Plaintiff’s negligence or the Defendant’s cause attributable to the Defendant. Therefore, the above assertion is without merit. Accordingly, the Defendant shall pay to the Plaintiff damages for delay calculated at each rate of 15% per annum as stipulated in the Civil Act from February 17, 2017, which is the following day after the Plaintiff was served with a notice of tax payment stating the Plaintiff’s declaration of intent to demand performance, as the Plaintiff seeks from February 17, 2017, which is the date when the first instance judgment was rendered, until October 13, 2017, and from the next day until the day of full payment.