Cal. Unemp. Ins. Code § 13028.6

(a) For purposes of this division (and so much of Part 10 (commencing with Section 17001) and Part 10.2 (commencing with Section 18401) of Division 2 of the Revenue and Taxation Code as relates to this division), any payment to an individual of sick pay which does not constitute wages (determined without regard to this subdivision), if at the time the payment is made a request that such sick pay be subject to withholding under this division is in effect, shall be treated as if it were a payment of wages by an employer to an employee for a payroll period.
(b) For purposes of this subdivision, “sick pay” means any amount which satisfies both of the following:
1. (1) Is paid to an employee pursuant to a plan to which the employer is a party.
2. (2) Constitutes remuneration or a payment in lieu of remuneration for any period during which the employee is temporarily absent from work on account of sickness or personal injuries.
(c) If a payee makes a request that any sick pay be subject to withholding under this chapter, the amount to be deducted and withheld under this chapter from any payment to which that request applies shall be an amount (not less than a minimum amount determined by the Franchise Tax Board) specified by the payee in that request. The amount deducted and withheld with respect to a payment which is greater or less than a full payment shall bear the same relation to the specified amount as that payment bears to a full payment.
1. (1) A request that any sick pay be subject to withholding under this chapter shall satisfy all of the following:
  1. (A) Shall be made by the payee in writing to the person making the payments and shall contain the social security number of the payee.
  2. (B) Shall specify the amount to be deducted and withheld from each full payment.
  3. (C) Shall take effect with respect to payments made more than seven days after the date on which that request is furnished to the payer, or as the department shall by regulations prescribe. That request may be changed or terminated by furnishing to the person making the payments a written statement of change or termination which shall take effect in the same manner as provided in the preceding sentence. At the election of the payer, any such request (or statement of change or revocation) may take effect earlier than as provided in this subparagraph.
2. (2) Any sick pay paid pursuant to a collective bargaining agreement between employee representatives and one or more employers which contains a provision specifying that this paragraph is to apply to sick pay paid pursuant to that agreement and contains a provision for determining the amount to be deducted and withheld from each payment of that sick pay as follows:
  1. (A) The requirement of paragraph (3) of subdivision (a) that a request for withholding be in effect shall not apply.
  2. (B) Except as provided in Section 13026, the amounts to be deducted and withheld under this chapter shall be determined in accordance with that agreement.
    The preceding sentence shall not apply with respect to sick pay paid pursuant to any agreement to any individual, unless the social security number of that individual is furnished to the payer and the payer is furnished with that information as is necessary to determine whether the payment is pursuant to the agreement and to determine the amount to be deducted and withheld.