(1) As soon as reasonably possible after June 30 of each year, the Director of Banking and Finance shall estimate the total sum required for the purposes set forth in section 8-604 for the succeeding fiscal year. The director shall also estimate the total sum expected to be collected pursuant to section 8-603. The director shall use the difference between the estimate of the total sum required and the estimate of the total sum to be collected as the basis for the assessment to be levied.

(2) The assessment upon each financial institution shall be based upon the total assets of each financial institution, as reported in each financial institution's report of condition prepared for the period ending June 30 of each year, and, after June 30, 2009, may further be based upon the total amount of fiduciary and related assets and the total amount of off-balance-sheet receivables as reported in each financial institution's report of condition prepared for the period ending June 30 of each year.

(3) The director shall have the authority to prorate the assessment for any financial institution or entity which surrenders its charter or license or receives its charter or license during the assessment period. Proration shall be based on the number of months the financial institution held its charter or license. Any portion of a month shall be counted as one month.

(4) If the estimated sum levied and collected is insufficient to defray the expenditures for the fiscal year for which it was made, a special assessment may be levied and collected in like manner for the balance of the fiscal year.