The Commissioner promptly shall review the assessment allocation percentages calculated by the Association. Unless the Commissioner finds the calculation to be inaccurate, the Commissioner shall authorize each Association member to impose an assessment surcharge on each policy of motor vehicle liability insurance or motor vehicle physical damage insurance that is written or renewed in the State during the 1-year period beginning on the next July 1 following notice of the assessment. Subject to § 20-407 of this subtitle, the assessment surcharge shall be calculated by applying the appropriate assessment allocation percentage that is adjusted for any excess or shortfall to the premium at the inception or renewal of the policy. The assessment surcharge may not be: subject to change or refund; or considered premium income for the State premium tax or the payment of commissions. In conformity with §§ 20-405 through 20-409 of this subtitle, each year the Fund shall impose an assessment surcharge on all of its policyholders as if the Fund were a member of the Association. The Fund may not make a payment to the Insufficiency Assessment Reserve Fund. The Fund shall account separately for the assessment surcharges that the Fund assesses and receives.