N.H. Rev. Stat. Ann. § 402:15-b

No insurer authorized and licensed to issue policies of insurance other than life and accident and health insurance and to transact business in this state shall demand or make mandatory upon any agent so licensed in this state, any system of direct billing to the insured by the insurer unless such system shall be approved, accepted and endorsed by any such agent in writing, on a form prescribed by the commissioner. No insurer authorized and licensed to issue policies of insurance other than life and accident and health insurance and to transact business in this state shall cancel an agent's book of business with such insurer in its entirety or in part following an agent's decision not to accept a direct billing proposal advanced by the said insurer wherein such cancellation can be attributed to the agent's decision not to accept a system of direct billing to the insured.