a. Required counterclaim. A defendant must file a counterclaim for any claim that the defendant has against the plaintiff, if the defendant's claim arises out of same transaction, occurrence, or event that is described in the plaintiff's complaint. [ARCP 13(a)]

b. Permitted counterclaim. A defendant may file a counterclaim for any claim that the defendant has against the plaintiff but that does not arise out of the transaction, occurrence, or event that is described in the plaintiff's complaint. [ARCP 13(b)]

c. Filing a counterclaim with the answer; failure to file a counterclaim. A defendant must file a counterclaim at the time the defendant files an answer under Rule 116. If a defendant fails to file a counterclaim with an answer, the defendant may file a motion under Rule 119(a) requesting that the court allow the defendant to file an amended answer with a counterclaim. [ARCP 13(f)]

d. Cross-claim. In a case where there are two or more defendants, a defendant may state as a cross-claim any claim that the defendant has against another defendant arising out of the same transaction, occurrence, or event that is described in the plaintiff's complaint. The cross-claim must be stated at the time the defendant files an answer or other response to the complaint, unless the court allows an amendment under Rule 119(a). [ARCP 13(g)]

e. Filing a response to a counterclaim or a cross-claim. A party who is served with a counterclaim or a cross-claim must file a written response with the court pursuant to the provisions of Rule 116 and within the time provided in Rule 114(b). [ARCP 12(a)]

f. Counterclaim or cross-claim exceeding the jurisdiction of the justice court. If a claim filed pursuant to this rule exceeds the jurisdiction of the justice court, the lawsuit must be transferred as provided by law. [ARCP 13(c). See also A.R.S. § 22-201(G)]