Cal. Rev. & Tax. Code § 2961

Any excess in the proceeds of the sale over the taxes, penalties, and costs shall be returned to the owner of the property. Until claimed the excess shall be deposited in the county treasury, subject to the order of the owner or his successor in interest. Any excess in the proceeds of any sale heretofore or hereafter made becomes the property of the county if not claimed within three years after the date of sale.