N.H. Rev. Stat. Ann. § 99:6-b

Any person who is employed by a town, a village district, a school district, a city, or a county, and who subsequently becomes a state employee because the functions of his employment and his job with that political subdivision are taken over by the state, may count the time spent as an employee of a political subdivision as continuous with his present service as a state employee in order to obtain all benefits as a state employee. This section shall provide credit for past service as an employee of a political subdivision for compensation and benefit purposes for persons who enter state service on or after the effective date of this act.