Section 907. Pleadings; subsequent pleading containing cause of action

(a)
  Counterclaim. The plaintiff may reply to a counterclaim but shall not be
  required to do so  except  by  court  order.  If  the  plaintiff  elects
  voluntarily  to  reply,  he shall do so within ten days after service of
  the answer containing the counterclaim. In the absence of  a  reply  the
  allegations of the counterclaim shall be deemed denied by the plaintiff.
  An  answer  containing  a counterclaim against the plaintiff and another
  person shall be replied to by such other person, as required by  CPLR  §
  3019  (d), within the time provided in § 402 of this act, based upon the
  time and method of service.
    (b) Cross-claim. A cross-claim shall be answered within ten days after
  the answer containing it is served.
    (c)  Third-party  claim  and  claim  by   defendant   stakeholder.   A
  third-party  complaint,  and  an  interpleader  complaint  served  by  a
  defendant stakeholder under CPLR § 1006 (b), shall  be  answered  within
  the  time  provided in § 402 of this act, based upon the time and method
  of service.