Cal. Rev. & Tax. Code § 25116

Notwithstanding paragraph (1) of subdivision (a) of Section 23051.5, when provisions of this article refer to provisions of the Internal Revenue Code that do not otherwise apply for purposes of Part 10.2 (commencing with Section 18401) or this part, the term “Internal Revenue Code” means Title 26 of the United States Code, including all amendments thereto, as in effect for federal purposes for the taxable period, except as otherwise specifically provided in this article.