N.D. Cent. Code § 57-32-03
On or before the thirty-first day of March in each year, the tax commissioner shall provide each company assessed under the provisions of this chapter a statement of its taxes due for the preceding year, with the valuations and taxes assessed in each case. Such taxes are due upon the fifteenth day of April next following the date of the statement of taxes due. The taxes become delinquent on the first day of May next following the due date and, if not paid on or before said date, are subject to a penalty of two percent and, on June first following delinquency, an additional penalty of two percent and, on July first following delinquency, an additional penalty of two percent and, an additional penalty of two percent on October fifteenth following delinquency. From and after January first of the year following the year in which the taxes became due and payable, simple interest at the rate of twelve percent per annum upon the principal of the unpaid taxes must be charged until such taxes and penalties are paid, with such interest charges to be prorated to the nearest full month for a fractional year of delinquency. All the provisions of the law respecting delinquency of personal property assessments generally so far as may be consistent with the provisions of this chapter are applicable equally to the assessments and taxes provided for in this chapter.
N.D.C.C. § 57-32-03