N.J. Stat. Ann. § 43:15B-2

The amounts of any such deferred salary shall be determined by agreement between the employer and the employee, subject to any limitations which the employer may establish. The total amount of the salary deferred pursuant hereto for any year shall be in addition to any contributions made in such year on behalf of any employee in accordance with section 7 of P.L.1963, c. 123 (C. 52:18A-113).