N.D. Cent. Code § 57-34-04.1: Tax commissioner to audit returns and state board of equalization to assess tax

The tax commissioner shall proceed to audit the returns of telecommunications carriers not later than three years after the due date of the return, or three years after the return was filed, whichever period expires later. The state board of equalization shall assess the tax and, if any additional tax is found due, the tax commissioner shall notify the taxpayer in detail as to the reason for the increase.