Cal. Unemp. Ins. Code § 13050
(a) Every employer or person required to deduct and withhold from an employee a tax under Section 986, 3260, or 13020, or who would have been required to deduct and withhold a tax under Section 13020 (determined without regard to Section 13025) if the employee had claimed no more than one withholding exemption, shall furnish to each employee in respect of the remuneration paid by the person to the employee during the calendar year, on or before January 31 of the succeeding year, or, if his or her employment is terminated before the close of the calendar year, on the day on which the last payment of remuneration is made, a written statement showing all of the following:
(c) If, during any calendar year, any person makes a payment of third-party sick pay to an employee, that person shall, on or before January 15 of the succeeding year, furnish a written statement to the employer in respect of whom the payment was made showing all of the following:
(3) The total amount, if any, deducted and withheld from that sick pay under this division. For purposes of the preceding sentence, the term “third-party sick pay” means any sick pay, as defined in subdivision (b) of Section 13028.6, which does not constitute wages for purposes of this division, determined without regard to subdivision (a) of Section 13028.6.