N.H. Rev. Stat. Ann. § 7:25

Whenever the attorney general may require the attendance of any such person, agent, trustee, fiduciary, beneficiary, institution, association, corporation, or political agency, as provided in RSA 7:24, he shall issue a notice setting the time and place when such attendance is required and shall cause the same to be delivered or sent by registered mail to such person, agent, trustee, fiduciary, beneficiary, institution, association, corporation, or political agency at least 14 days before the date fixed in the notice for such attendance.