N.H. Rev. Stat. Ann. § 235:5

Where, under these provisions, improvements are made within the limits of compact sections of cities and towns or upon highways not regularly maintained by the state, the same shall thereafter be maintained by said city or town to the satisfaction of the commissioner of transportation. In case any city or town fails to properly maintain the highway, it shall be maintained under the direction of the commissioner at the expense of the state, and the cost shall be paid by such city or town to the state treasurer. In default of such payment the state treasurer may issue an extent as provided in RSA 85 for the collection of such payment.