(a) The annual program fee determined for the current calendar year is an estimated fee based upon the fee determined for the preceding calendar year. Once the current calendar year ends on December 31st, it may be necessary for the department to redetermine the fee based upon whether the actual amounts of hazardous waste generated or received by each regulated entity were overestimated or underestimated.

(b) A person having to pay an annual program fee may request that the annual program fee for that calendar year be redetermined based upon the actual volume of hazardous waste generated or received during that calendar year. This request must be made under the provisions of section 481.9 of this Title, except that time limits are extended as provided in section 481.4 of this Title.

(c) The department may change a program fee for a calendar year at any time during that calendar year or within the next three calendar years.

(d) If a person wants to challenge the correctness of the department's change, that person must follow the procedures set forth in section 481.9 of this Title.

(e) If the department finds that the person overpaid an annual program fee due for that calendar year, the department will refund or credit the amount of that overpayment.