California Code, Code of Civil Procedure - CCP § 1263.140

Subject to Section 1263.110, if a new trial is ordered by the trial or appellate court and the new trial is not commenced within one year after the commencement of the proceeding, the date of valuation is the date of the commencement of such new trial unless, in the interest of justice, the court ordering the new trial orders a different date of valuation.