(1) If the Tax Commissioner is not satisfied with the return or returns of the tax or the amount of tax required to be paid to the state by any person, he or she may compute and determine the amount required to be paid upon the basis of the facts contained in the return or returns or upon the basis of any information within his or her possession or which may come into his or her possession. One or more deficiency determinations of the amount due for one or more than one period may be made. To the amount of the deficiency determination for each period shall be added a penalty equal to ten percent thereof or twenty-five dollars, whichever is greater. In making a determination, the Tax Commissioner may offset overpayments for a period or periods, together with interest on the overpayments, against underpayments for other period or periods, against penalties, and against the interest on the underpayments.
The interest on underpayments and overpayments shall be computed in the manner set forth hereinafter.