(1) The department may, at its discretion, recalculate the tax rate for any employer if it determines, within three years of the July 1 computation date, that the rate as originally computed was erroneous.

(2) Except as provided in subsection (1) of this section, an employer must submit a written request for rate review or recalculation before the department will recalculate a rate. This does not apply if the department determines that the department's error caused an incorrect tax rate.

(3) The department will not recalculate a tax rate at the request of the employer more than once in a calendar year.