California Code, Education Code - EDC § 44916

The classification shall be made at the time of employment and thereafter in the month of July of each school year.  At the time of initial employment during each academic year, each new certificated employee of the school district shall receive a written statement indicating his employment status and the salary that he is to be paid.  If a school district hires a certificated person as a temporary employee, the written statement shall clearly indicate the temporary nature of the employment and the length of time for which the person is being employed.  If a written statement does not indicate the temporary nature of the employment, the certificated employee shall be deemed to be a probationary employee of the school district, unless employed with permanent status.