Cal. Rev. & Tax. Code § 24946

If the election provided in Section 24944(a) is made by the taxpayer and such other property or such stock was purchased before the beginning of the last taxable year in which any part of the gain upon such conversion is realized, any deficiency, to the extent resulting from such election, for any taxable year ending before such last taxable year may be assessed (notwithstanding the provisions of Section 19057 or the provisions of any other law or rule of law which would otherwise prevent such assessment) at any time before the expiration of the period within which a deficiency for such last taxable year may be assessed.