Cal. Education Code § 26504

The employer may enter into a collective bargaining agreement to pay a different employer contribution rate and a different employee contribution rate, provided all of the following conditions are met: (a) The sum of the employee contributions and employer contributions for each participant shall equal or exceed 8 percent of salary. (b) The employee contribution rate may exceed the employer contribution rate but in no event shall the employer contribution rate be less than 4 percent. (c) The employee contribution rate shall not be less than the employer contribution rate. If the terms of a collective bargaining agreement that is in effect on January 1, 2014, would be impaired by this subdivision, this subdivision shall not apply to the employer and participants subject to that contract until the expiration of that contract. A renewal, amendment, or any other extension of that contract shall be subject to the requirements of this subdivision. (d) The employee contribution rate and employer contribution rate shall be the same for each participant employed by the employer. (e) The employee contribution rate and employer contribution rate shall be in one-quarter percent increments. (f) The employee contribution rate and employer contribution rate as determined under the collective bargaining agreement shall become effective on the first day of the plan year following notification to the system and shall remain in effect for at least one plan year. However, the employee contribution rate and the employer contribution rate as determined under the collective bargaining agreement may become effective as of the first day of the plan year in which notice is given if it is so provided in the collective bargaining agreement and if a lump-sum contribution is made to the plan equal to the additional employee and employer contributions, if any, that would have been required if the contribution rates had been in effect on the first day of the plan year. Interest shall be credited at the minimum interest rate with respect to the lump-sum contribution commencing with the first month after the contribution is made. (g) The employer has filed notice of the employee contribution rate and the employer contribution rate on a form prescribed by the system.