N.H. Rev. Stat. § 100-A:33
Any person who, as of May 31, 1989, is actively employed and is earning benefits and making contributions in accordance with the provisions of any predecessor system of the New Hampshire retirement system shall, effective August 1, 1989, earn benefits and make contributions under the provisions of this chapter and, upon retirement, death, disability, or termination shall be considered to have been a full member of the New Hampshire retirement system for the entire period of creditable service in either system as provided in RSA 100-A:4, I; provided, however, that any such person may elect, by notification in writing to the board of trustees on or before July 15, 1989, to continue to make contributions and earn benefits under the provisions of the predecessor system; and any such election shall thereafter be irrevocable.
RSA 100-A:33
1969, 282:1. 1989, 238:3, eff. May 24, 1989.