N.D. Cent. Code § 57-20-01
All real and personal property taxes and yearly installments of special assessment taxes become due on the first day of January following the year for which the taxes were levied. The first installment of real estate taxes, all personal property taxes, and yearly installments of special taxes become delinquent after the first day of March following and, if not paid on or before said date, are subject to a penalty of three percent, and on May first following an additional penalty of three percent, and on July first following an additional three percent, and an additional penalty of three percent on October fifteenth following. From and after January first of the year following the year in which the taxes become due and payable, simple interest at the rate of twelve percent per annum upon the principal of the unpaid taxes on personal property must be charged until the taxes and penalties are paid, with the interest charges to be prorated to the nearest full month for a fractional year of delinquency. The second installment of real estate taxes becomes delinquent after October fifteenth, and, if not paid on or before that date becomes subject to a penalty of six percent.
N.D.C.C. § 57-20-01