N.J. Stat. § 43:10-18.29
Where any such employee has had prior elective or appointive service in any State or municipal office or position, such employee shall be given credit for pension purposes hereunder for such prior service, in addition to his total county service, upon payment into the fund, in such manner as shall be determined by the pension commission, of all arrears, with interest as the pension commission shall determine to be due in order to give such employee the same standing as a member of said fund as all other members who joined said pension fund when the law providing for such fund became effective, in which case the maximum rate of interest shall not exceed the average rate of earnings of the investments of said fund and the maximum length of time for the payment of arrears shall be 5 years from the date of the application to join the fund; or if so requested upon written application, the regular deductions from the salary of such employee shall commence upon the filing of such written application and he shall be entitled to the same benefits as a new employee then joining the fund would receive.
N.J.S. § 43:10-18.29