In order to defray the costs of an examination pursuant to § 6.2-1309 and of supervision and regulation by the Commission, every credit union shall pay an annual fee, to be calculated in accordance with a schedule set by the Commission. The schedule shall bear a reasonable relationship to the total assets of various individual credit unions, to the actual cost of their respective examinations, and to other factors relating to their supervision and regulation. Fees shall be assessed pursuant to this section on or before March 1 each year. All fees so assessed shall be paid by the credit union to the state treasury on or before March 31 following the assessment.