N.J. Stat. § 40:63-119
The commissioners before they enter upon the execution of their duties shall severally take and subscribe an oath that they will make such assessment fairly and impartially, according to the best of their skill and judgment, and thereupon shall at once proceed to perform the duties hereby imposed upon them. They shall, within sixty days, unless the court shall, before or after its expiration, extend the time, make a just and equitable assessment of the costs, damages and expenses of the improvements, or any part thereof, upon the lands and real estate located in any of the territory of such municipality fronting on the improvement or works which are peculiarly benefited thereby, in proportion to and not in excess of the advantage each shall be deemed to acquire.
If the costs, damages, and expenses shall exceed the amount of the benefits, the excess shall be assessed upon and paid by the municipalities respectively so jointly contracting in accordance with the provisions in the joint contract for the apportionment or percentages of costs, damages and expenses among the jointly contracting municipalities.
N.J.S. § 40:63-119