Ed. Code, § 24102

(a) The board may authorize payment of a disability retirement allowance under this part to any member who is qualified upon application by the member, the member’s guardian or conservator, or the member’s employer, if the application is submitted on a properly executed form prescribed by the system during any one of the following periods:

(1) While the member is employed and has performed creditable service within the four months previous to application, or while the member is on a compensated leave of absence.

(2) While the member is physically or mentally incapacitated for performance of service and the incapacity has been continuous from the last day of actual performance of service for which compensation is payable to the member.

(3) While the member is on a leave of absence without compensation, granted for reason other than mental or physical incapacity for performance of service, and within four months after the last day of actual performance of service for which compensation is payable to the member, or within 12 months of that date if the member was on an employer-approved leave to study at an approved college or university.

(4) Within four months after the termination of the member’s employment subject to coverage under the Defined Benefit Program, if the application was not made under paragraph (2) and was not made more than four months after the last day of actual performance of service for which compensation is payable to the member.

(b) The member is not qualified to receive a disability retirement allowance if the member is applying because of a physical or mental condition that existed at the time the most recent membership in the Defined Benefit Program commenced and which remains substantially unchanged at the time of application.