N.H. Rev. Stat. Ann. § 83-F:3

On or before December 1 of the tax year, the commissioner shall determine the market value of utility property for the purposes of this chapter by utilizing generally accepted appraisal methods and techniques. Market value means the property's full and true value as defined under RSA 75:1. In the case of regulated public utilities as defined in RSA 362:2, the commissioner shall hold a single public hearing annually prior to performing assessments, in order to receive public input on assessments under this chapter. Notice of such determination shall be given to the taxpayer within 15 days of the commissioner's determination.