N.J. Stat. § 40A:10-36.2
The governing body of any local unit that has established a joint insurance fund may by resolution or ordinance, as appropriate, establish a joint insurance revolving fund into which may be deposited any refunds paid to the local unit by the joint insurance fund to be dedicated for the payment of liabilities to the fund in future years. In no event shall amounts deposited in a joint insurance revolving fund exceed the annual amount contributed by the local unit to the joint insurance fund during the prior year.
Moneys appropriated from the joint insurance revolving fund shall be used by the local unit to cover losses attributable to claims being paid by the joint insurance fund in future years which exceed contributions paid into the joint insurance fund by the local unit.
N.J.S. § 40A:10-36.2