(a) The association is composed of each insurer, including a Lloyd’s plan and a reciprocal or interinsurance exchange, authorized to write and writing liability insurance, including automobile liability insurance, on a direct basis in this state, other than:
(1) a farm mutual insurance company authorized under Chapter 911; and
(2) a county mutual insurance company authorized under Chapter 912.
(b) An insurer that is a member of the association must remain a member as a condition of the insurer’s authority to engage in the business of the insurance described by Subsection (a).

(c) Each association member participates in the writings, expenses, and losses of the association in the proportion that the net direct premiums of the member, excluding the portion of premiums attributable to the operation of the association, written during the preceding calendar year bears to the aggregate net direct premiums written in this state by all association members.
(d) The association shall annually determine a member’s participation in the association on the basis of the net direct premiums written by the member during the preceding calendar year, as reported in the annual statements and other reports the member files as required by the department.