2010 New York Code
CVP - Civil Practice Law & Rules
Article 30 - (3001 - 3045) REMEDIES AND PLEADING
R3025 - Amended and supplemental pleadings.

Rule  3025. Amended and supplemental pleadings. (a) Amendments without
  leave. A party may amend his pleading once without leave of court within
  twenty days after its service, or at any  time  before  the  period  for
  responding  to  it  expires,  or  within  twenty days after service of a
  pleading responding to it.
    (b) Amendments and supplemental pleadings by leave. A party may  amend
  his pleading, or supplement it by setting forth additional or subsequent
  transactions  or  occurrences,  at  any  time  by  leave  of court or by
  stipulation of all parties. Leave shall be freely given upon such  terms
  as may be just including the granting of costs and continuances.
    (c)  Amendment  to  conform  to  the  evidence.  The  court may permit
  pleadings to be amended before or after judgment to conform them to  the
  evidence, upon such terms as may be just including the granting of costs
  and continuances.
    (d)  Responses  to  amended  or  supplemental  pleadings. Except where
  otherwise prescribed by law or order of the court,  there  shall  be  an
  answer  or  reply to an amended or supplemental pleading if an answer or
  reply is  required  to  the  pleading  being  amended  or  supplemented.
  Service  of  such  an  answer  or reply shall be made within twenty days
  after service of the  amended  or  supplemental  pleading  to  which  it
  responds.