Section 416 - Rates and reporting of rates(a) Every workers' compensation self-insurance group shall file and adhere to rates, rules and classifications pursuant to Chapter 26 of this title.(b) Premium contributions to the group shall be determined by applying the rates and rules to the appropriate classification of each member which may be adjusted by each member's experience credit or debit. Subject to approval by the Commissioner, premium contributions may also be reduced by an advance premium discount reflecting the group's expense levels and loss experience.(c) A group may contract with an advisory organization approved by the Commissioner for assistance in developing appropriate rates.(d) Each group shall be audited at least annually by an auditor acceptable to the Commissioner to verify proper classifications, experience rating, payroll and rates. A report of the audit shall be filed with the Commissioner in a form acceptable to the Commissioner. A group or any member thereof may request a hearing on any objections to the classifications. If the Commissioner determines that, as a result of an improper classification, a member's premium contribution is insufficient, the commissioner shall order the group to assess that member an amount equal to the deficiency. If the Commissioner determines that, as a result of an improper classification, a member's premium is excessive, the commissioner shall order the group to refund to the member the excess collected. The audit shall be at the expense of the group. 70 Del. Laws, c. 540, § 1.;