N.H. Rev. Stat. § 417:16
If any person shall ask to be excused from attending and testifying or from producing any books, papers, records, correspondence, or other documents at any hearing on the ground that the testimony or evidence required of such person may tend to be self-incriminating or subject such person to a penalty or forfeiture, and shall notwithstanding be directed to give such testimony or produce such evidence, the person must nonetheless comply with such direction, but shall not thereafter be prosecuted or subjected to any penalty or forfeiture for or on account of any transaction, matter or thing concerning which such person may testify or produce evidence pursuant thereto, and no testimony so given or evidence produced shall be received against the person upon any criminal action, investigation or proceeding; provided, however, that no such individual so testifying shall be exempt from prosecution or punishment for any perjury committed by such individual while so testifying and the testimony or evidence so given or produced shall be admissible against the individual upon any criminal action, investigation or proceeding concerning such perjury, nor shall the individual be exempt from the refusal, revocation, or suspension of any license, permission or authority conferred, or to be conferred, pursuant to the insurance law of this state. Any such individual may execute, acknowledge, and file in the office of the commissioner a statement expressly waiving such immunity or privilege in respect to any transaction, matter, or thing specified in such statement and thereupon the testimony of such person or such evidence in relation to such transaction, matter, or thing may be received or produced before any judge or justice, court, tribunal, grand jury or otherwise, and if so received or produced such individual shall not be entitled to any immunity or privilege on account of any testimony such individual may so give or evidence so produced.
RSA 417:16
1947, 189:1, par. 16. 1996, 238:17, eff. Jan. 1, 1997.