(1) The department shall calculate and compute from the returns the gross product yielded from the mine and its gross value for the year covered by the return. The department shall also calculate and compute the net proceeds yielded to the mine operator.  The net proceeds shall be ascertained and determined by subtracting from the gross value the deductions that are allowed to the operator of the mine. Allowable deductions are set forth in ARM 42.25.1111 through 42.25.1117.

(2) Each operator shall be notified of the assessment for each mine.  The taxpayer shall be notified of any changes made by the department when auditing the net proceeds return.