California Code, Government Code - GOV § 31649.1

Any employer who reemploys a member who is subject to the provisions of Chapter 43 (commencing with Section 4301) of Title 38 of the United States Code, shall, within 30 days after the date of that reemployment, provide information in writing as required by the board notifying the system of that reemployment, and shall provide the returning employee written notification of the right to purchase that service credit.