California Code
ARTICLE 1 - Individuals and Fiduciaries
Section 18531.5.

18531.5. For purposes of Section 443 of the Internal Revenue Code, where the spouses have different taxable years because of the death of either spouse, the joint return shall be treated as if the taxable years of both spouses ended on the date of the closing of the surviving spouse’s taxable year.

(Amended by Stats. 2016, Ch. 50, Sec. 105. (SB 1005) Effective January 1, 2017.)