N.H. Rev. Stat. Ann. § 383-E:1-104

The commissioner has the powers necessary or incidental to performing all of the commissioner's duties under this chapter, including the power to adopt rules as provided in this chapter in accordance with RSA 541-A. All rules previously adopted by the commissioner relating to the subject matter of this chapter shall be subject to RSA 541-A:17, except for rules adopted under RSA 394-A:7 which shall continue in full force and effect until amended or repealed.