Cal. Ins. Code § 11621.1

In the event an insurer discontinues writing automobile liability insurance in this state but retains its license to write that business, it shall continue to pay plan assessments and receive plan assignments until its quota or quotas established by its writings prior to discontinuance of business has or have been filled. However, if the automobile liability business of an insurer discontinuing the writing of that business in this state has been transferred to or reinsured by another insurer, the latter shall receive and assume the plan assignments and plan assessments of the insurer discontinuing business, as established by its writings prior to the transfer or agreement of reinsurance, until its quota or quotas has or have been filled, unless another insurer is allowed to assume those obligations.