N.J. Stat. § 43:13-22.16a
Any employee member, or eligible employee upon becoming a member of a retirement system, established pursuant to the act to which this act is a supplement, may purchase and receive prior service credit for time served in active service in the Armed Forces of the United States while a permanent employee of the city. Such member shall pay into the fund, in a lump sum or by regular payroll deduction installments approved by the pension commission, an amount equal to the contributions which a member would have been required to make for such a period based upon the member's salary, at the time of entering into active service in the armed forces, at the member's contribution rate in effect at the time of applying to make such purchase.
N.J.S. § 43:13-22.16a