1.    When the amount of taxes due is understated on a return because of a mathematical or clerical error, the commissioner shall notify the company of the error and the    amount of additional taxes due. This notice is not a notice of deficiency and the company has no right to protest.

2.    If upon an audit the commissioner finds additional taxes due, the commissioner shall notify the company and the state board of equalization of the deficiency in the tax amount. A notice of deficiency must be sent to the company by first-class mail and must state the amount of additional taxes due and set forth the reasons for the increase.

3.    A company has thirty days from the date of mailing of the notice of deficiency to file a written protest with the state board of equalization objecting to the assessment of additional taxes due. The protest must set forth the basis for the protest and any other information that may be required by the state board of equalization. If a company fails to file a written protest within the time provided, the amount of additional taxes stated in the notice of deficiency becomes finally and irrevocably fixed. If a company protests only a portion of the commissioner’s finding, the portion that is not protested becomes finally and irrevocably fixed.

4.    If a protest is filed, the state board of equalization shall reconsider the assessment of additional taxes due.

5.    Within six months after the protest is filed, the state board of equalization shall mail to the company a notice of reconsideration and assessment which must respond to the company’s protest and assess the amount of any additional taxes due. The amount set forth in that notice becomes finally and irrevocably fixed unless the company brings an action against the state in district court within six months of the mailing of the notice of reconsideration and assessment.