N.J. Stat. § 43:15A-75.2
Notwithstanding any other law to the contrary, a member of the Public Employees' Retirement System who is employed by a county hospital in a county of the first class according to the latest federal decennial census may purchase credit for temporary service which resulted, without interruption, in permanent employment by agreeing to make contributions covering the service. The employer shall not be liable for payment to the retirement system by reason of the member's purchase of service credit under this section, and all contributions required with respect to the liability created by the purchase shall be made by the member. The member may purchase service credit under this section by making payments to the retirement system either in a lump sum or in regular monthly installments pursuant to formulas, rules and regulations as the Division of Pensions may establish.
Notwithstanding any other provision of this act to the contrary, if, upon retirement, the member's payment for the purchase of temporary service credit is insufficient to provide for the additional retirement benefit attributable to this service, the difference may be assessed to the member, or a pro rata benefit may be granted based on the member's payment for the purchase prior to the date of retirement, at the election of the member.
If a member elects to purchase credit for temporary service and retires prior to completing payment therefor, the member shall receive a pro rata credit for the service purchased prior to the date of retirement, but if the member elects at the time of retirement, the member may make an additional lump sum payment at that time as will be necessary to provide full credit.
N.J.S. § 43:15A-75.2