N.Y. C.P.L.R. 1007

§ 1007. When third-party practice allowed. After the service of his\nanswer, a defendant may proceed against a person not a party who is or\nmay be liable to that defendant for all or part of the plaintiff's claim\nagainst that defendant, by filing pursuant to section three hundred four\nof this chapter a third-party summons and complaint with the clerk of\nthe court in the county in which the main action is pending, for which a\nseparate index number shall not be issued but a separate index number\nfee shall be collected. The third-party summons and complaint and all\nprior pleadings served in the action shall be served upon such person\nwithin one hundred twenty days of the filing. A defendant serving a\nthird-party complaint shall be styled a third-party plaintiff and the\nperson so served shall be styled a third-party defendant. The defendant\nshall also serve a copy of such third-party complaint upon the\nplaintiff's attorney simultaneously upon issuance for service of the\nthird-party complaint on the third-party defendant.\n