N.H. Rev. Stat. Ann. § 74:5

The selectmen or assessors shall cause inventory blanks to be mailed, postage prepaid, to the last known address of all persons and corporations known or believed to own taxable property in their towns and cities or, alternatively, to be hand delivered by such means as the selectmen or assessors shall deem convenient and legally sufficient. Either method of distribution shall occur on or before March 25 of each year.