N.H. Rev. Stat. § 48-B:4
Any building, or other thing, erected or affixed under any such lease shall be taxed to the lessee thereof or his assigns in the same manner and to the same extent as if such lessee or his assigns were the owners of the land in fee; provided that no part of the value of the land shall be included in any such assessment. The municipality may exercise all remedies provided generally for the collection of taxes and any such lease-hold estate may be sold or taken by the municipality for the nonpayment of any taxes assessed as aforesaid in the manner provided by law for the sale or taking of real estate for nonpayment of local taxes. The municipality shall include in any lease of such air rights a provision whereby the lessee agrees, in the event that the foregoing tax provision is determined by a court of competent jurisdiction to be inapplicable, to pay annually to the municipality a sum of money in lieu of such taxes which would otherwise be assessed thereon in such year.
RSA 48-B:4
1969, 493:2, eff. Sept. 1, 1969.