California Code, Education Code - EDC § 44901

(a) A certificated employee who has served in a position or positions requiring certification qualifications in two or more districts, each having an average daily attendance of 250 or more and governed by governing boards of identical personnel, for a total of three complete consecutive school years, upon being elected for the fourth consecutive school year to a position or positions requiring certification qualifications in any of the districts, shall at the commencement of the fourth consecutive school year be classified as a permanent employee of the last district in which he or she was employed prior to his or her election for the fourth consecutive school year.

Where there are two or more districts, each having an average daily attendance of 250 or more and governed by governing boards of identical personnel, a certificated employee who has served in one of the districts for three complete consecutive school years, upon being elected for the fourth consecutive school year to a position or positions requiring certification qualifications in any of the districts, shall at the commencement of the fourth consecutive school year be classified as and become a permanent employee of the last district in which he or she was employed prior to his or her election for the fourth consecutive school year.

This subdivision shall apply only to probationary employees whose probationary period commenced prior to the 1983-84 fiscal year.

(b) A certificated employee who has served in a position or positions requiring certification qualifications in two or more districts, each having an average daily attendance of 250 or more and governed by governing boards of identical personnel, for a total of two complete consecutive school years, upon being elected for the third consecutive school year to a position or positions requiring certification qualifications in any of the districts, shall at the commencement of the third consecutive school year be classified as a permanent employee of the last district in which he or she was employed prior to his or her election for the third consecutive school year.

Where there are two or more districts, each having an average daily attendance of 250 or more and governed by governing boards of identical personnel, a certificated employee who has served in one of the districts for two complete consecutive school years, upon being elected for the third consecutive school year to a position or positions requiring certification qualifications in any of the districts, shall at the commencement of the third consecutive school year be classified as and become a permanent employee of the last district in which he or she was employed prior to his or her election for the third consecutive school year.

The governing board shall notify the employee, on or before March 15 of the employee's second complete consecutive school year of employment by the districts in a position or positions requiring certification qualifications, of the decision to reelect or not reelect the employee for the next succeeding school year to such a position.  In the event that the governing board does not give notice pursuant to this section on or before March 15, the employee shall be deemed reelected for the next succeeding school year.

This subdivision shall apply only to probationary employees whose probationary period commenced during the 1983-84 fiscal year or any fiscal year thereafter.