(a) The association shall assess member insurers the amount necessary to pay:
(1) the association's obligations under Section 462.302 and the expenses of handling covered claims subsequent to an insolvency; and
(2) other expenses authorized by this chapter.
(b) The assessment of each member insurer must be in the proportion that the net direct written premiums of the insurer for the calendar year preceding the assessment bear to the net direct written premiums of all member insurers for that year.