(a) This chapter shall apply only to domestic mutual fire insurers heretofore and now doing business on the assessment premium plan.
(b) For the purposes of this chapter an insurer “doing business on the assessment premium plan” is one which depends in whole or substantial part upon special or regular assessments levied upon its members, either prior to or after a loss, for the payment of losses and expenses. This provision shall not be deemed to prevent any such insurer from collecting from each member such initial amount as it may deem proper prior to or at the time of the effectuation of the member's insurance and shall not be deemed to prohibit the acquisition, accumulation and maintenance of surplus or unallocated funds.