Cal. INS § 10192.23

(a) If a Medicare supplement policy or certificate replaces another Medicare supplement policy or certificate, the replacing issuer shall waive any time periods applicable to preexisting conditions, waiting periods, elimination periods, and probationary periods in the new Medicare supplement policy or certificate for similar benefits to the extent that time was spent under the original policy.

(b) If a Medicare supplement policy or certificate replaces another Medicare supplement policy or certificate that has been in effect for at least six months, the replacing policy shall not provide any time period applicable to preexisting conditions, waiting periods, elimination periods and probationary periods for benefits similar to those contained in the original policy or certificate.