I am a GC working on building a new home for a client. The Client refuses to pay the fourth and last payment, due to a discrepancy with the elevator installation. We have stopped work, and need the payment in order to continue.
You should start here to familiarize yourself with NJ lien laws: https://www.levelset.com/mechanics-lien/new-jersey-lien-law-faqs/
Filing a lien on residential projects in NJ falls under a seperate statute. You must have a written contract to file a lien in NJ. You will need to file a Notice of Unpaid Balance (the "NUB") within 60 days of when you last performed contract work. You also need to request and receive a favorable decision from the American Arbitration Association(the "AAA"). Once you have timely filed the NUB and received the decision from the AAA, you will need to file the lien within 120 days of when you last performed contract work on the property which you seke to lien.