N.H. Rev. Stat. § 71-B:19
Any such assessment or reassessment if satisfactory to the board shall when completed be returned to the clerk of the city or town, and shall be treated as an original assessment and the selectmen or assessors shall assess the taxes on the property accordingly. If it is advisable or necessary for the commissioner of revenue administration to make such assessment or reassessment it shall when completed be returned to the clerk of such city or town and shall be treated as an original assessment and the selectmen or assessors shall assess the taxes on the property accordingly. The tax collector shall have the same power to enforce payment of the tax, interest and penalties as though such assessment or reassessment were imposed on April 1. The lien provided in RSA 80:19 shall take effect on that portion of the property supplementally assessed for a period of 18 months following the actual time of the supplemental assessment.
RSA 71-B:19
1973, 544:2, eff. Sept. 1, 1973.