Indiana Code Title 34. Civil Law and Procedure § 34-51-2-16

Sec. 16. A nonparty defense that is known by the defendant when the defendant files the defendant's first answer shall be pleaded as a part of the first answer.  A defendant who gains actual knowledge of a nonparty defense after the filing of an answer may plead the defense with reasonable promptness.  However, if the defendant was served with a complaint and summons more than one hundred fifty (150) days before the expiration of the limitation of action applicable to the claimant's claim against the nonparty, the defendant shall plead any nonparty defense not later than forty-five (45) days before the expiration of that limitation of action.  The trial court may alter these time limitations or make other suitable time limitations in any manner that is consistent with: