N.H. Rev. Stat. § 102:4
Any permanent fireman in this state who prior to July 1, 1967 accepted the provisions of this chapter shall continue to be entitled to the benefits of this system thereafter, unless on or before November 30, 1967 or May 1, 1968 he files with the board of trustees, on a form prescribed by the board, a notice of his election to become a member as of January 1, 1968 or July 1, 1968 of the New Hampshire Retirement system as provided by RSA 100-A:3, II, in which event his entitlement to the benefits provided under this system shall cease as of December 31, 1967 or June 30, 1968. Any permanent fireman who prior to July 1, 1967 did not accept the provisions of this chapter or any person who becomes a permanent fireman on or after that date shall be ineligible to make application to accept the provisions of this chapter and shall not be entitled to the benefits hereof.
RSA 102:4
1939, 154:4. 1941, 192:4. RL 220:4. RSA 102:4. 1967, 134:12, eff. July 1, 1967.