The contingent liability of a member of such company may, with the approval of the commissioner, be limited to one or more times the annual premium as computed for the policy and the company may issue a policy without contingent liability to the member if at the time of issuance the net premium written to surplus as to policyholders does not exceed four to one and the company maintains unearned premium and other reserves on the same basis as that required of domestic insurers transacting like kinds of insurance. In the absence of such limitation of contingent liability each member shall be liable for his or her pro rata share of losses and expenses of the company, including a reasonable contribution to a surplus fund.