N.H. Rev. Stat. § 79-E:4-c
A city or town may adopt the provisions of this section by vote of its legislative body, in accordance with the procedures described in RSA 79-E:3, to establish a housing opportunity zone. To be eligible for tax relief under this section, the qualifying structure and property shall be located within the housing opportunity zone established by the municipality. No less than one-third of the housing units constructed shall be designated for households with an income of 80 percent or less of the area median income as measured by the United States Department of Housing and Urban Development, or the housing units in a qualifying structure shall be designated for households with incomes as provided in RSA 204-C:57, IV. A qualifying structure under this section shall be eligible for tax assessment relief for a period of up to 10 years, beginning upon issuance of the certification of occupancy.
RSA 79-E:4-c