N.J. Ct. R. 4:58-1

(a) Except in a matrimonial action or an action adjudicated in the Special Civil Part, any party may, at any time more than 20 days before the actual trial date, serve on any adverse party, without prejudice, and file with the court, an offer to take a monetary judgment in the offeror’s favor, or as the case may be, to allow judgment to be taken against the offeror, for a sum stated therein (including costs). The offer shall not be effective unless, at the time the offer is extended, the relief sought by the parties in the case is exclusively monetary in nature. Any offer made under this rule shall not be withdrawn except as provided herein.

(b) If at any time on or prior to the 10th day before the actual trial date the offer is accepted, the offeree shall serve on the offeror and file a notice of acceptance with the court. The making of a further offer shall constitute a withdrawal of all previous offers made by that party. An offer shall not, however, be deemed withdrawn upon the making of a counter-offer by an adverse party but shall remain open until accepted or withdrawn as is herein provided. If the offer is not accepted on or prior to the 10th day before the actual trial date or within 90 days of its service, whichever period first expires, it shall be deemed withdrawn and evidence thereof shall not be admissible except in a proceeding after the trial to fix costs, interest, and attorney's fee. The fact that an offer is not accepted does not preclude a further offer within the time herein prescribed in the same or another amount or as specified therein.

(c) Except as otherwise provided under this Rule, prior to the service or filing of a notice of acceptance, an offeror may withdraw an offer by serving on the offeree and filing a notice of withdrawal with the court. An offer voluntarily withdrawn by the offeror shall not be subject to this Rule.