(1) The office shall ascertain on or before December 1 of each year whether the amounts estimated to be received from the regulatory assessment imposed under s. 624.515 for that calendar year, payable on or before the following March 1, as herein prescribed, shall result in an accumulation of funds in excess of the just requirements for which the assessment is imposed as set forth in s. 624.516; and if it determines that the imposition of the full amount of the assessment would result in such excess, it may reduce the percentage amount of the assessment for that calendar year to such percentage as may be necessary to meet the just requirements for which the assessment is imposed. (2) When a determination is made so reducing the amount of the assessment, the department shall make and issue its order setting forth such determination and fixing the amount of assessment for that calendar year, payable on or before March 1 of the following year, and shall mail a copy of such order to each insurer who, according to the records of the office, is subject to the assessment.