I. The excavation tax shall be assessed by the local assessing officials within 30 days after receipt of a report of excavated material form by such officials in the municipality in which the excavation took place. Interest as provided in N.H. Rev. Stat. § 72-B:6 shall be charged 30 days after the bills are mailed by the tax collector, on any tax which is due and payable and which remains unpaid.
II. [Repealed].