Cal. Rev. & Tax. Code § 24964

Whenever a taxpayer has realized gain or loss upon the receipt after January 1, 1928, at a time when it was subject to a tax under this part, of all or substantially all of the business or property of a taxpayer over which it exercised control within the meaning of Section 24564, and such gain or loss actually was not taken into account in the computation of taxes imposed by this part, the basis of the property or business acquired shall be the same as it was in the hands of the transferor.