(1) By December 1 of each calendar year, the commissioner shall determine the state unemployment insurance tax rate for the following year based on information available through the department.

(2) If the state unemployment insurance tax rate is determined to be zero percent pursuant to subsection (1) of this section, the contribution rate for all employers shall equal one hundred percent of the combined tax rate.

(3) If the state unemployment insurance tax rate is not zero percent as determined in this section, the combined tax rate shall be divided so that not less than eighty percent of the combined tax rate equals the contribution rate and not more than twenty percent of the combined tax rate equals the state unemployment insurance tax rate except for employers who are assigned a combined tax rate of five and four-tenths percent or more. For those employers, the state unemployment insurance tax rate shall equal zero and their combined tax rate shall equal their contribution rate.