(a) If any defendant has a claim against the plaintiff arising out of the transaction or occurrence that is the subject matter of the plaintiff's claim, which claim does not require for its adjudication the presence of third parties over whom the court cannot obtain jurisdiction, such claim must be asserted by the defendant at or before the hearing on plaintiff's claim or thereafter be barred.

(b) If any defendant has a claim against the plaintiff other than a compulsory counterclaim described in subsection (a) of this Code section, such claim may be asserted by the defendant at or before the hearing on the plaintiff's claim.

(c) If any defendant asserts a claim against the plaintiff, the defendant shall file with the court a statement of the claim in concise form and free from technicalities. The defendant shall sign and verify the statement of claim by oath or affirmation. At the request of a defendant, the judge or clerk may prepare the statement.

(d) If the amount of a counterclaim exceeds the jurisdictional limits of the magistrate court, the case shall be transferred to any court of the county which has jurisdictional limits which exceed the amount of the counterclaim. If there is more than one court to which the action may be transferred, the parties may agree on the court to which the action shall be transferred, and, in the absence of any agreement, the judge of the magistrate court shall determine the court to which the action shall be transferred. If there is no other court to which the action may be transferred, it shall be transferred to the superior court of the county.

(e) A counterclaim may in the discretion of the magistrate be tried either separately or jointly with the plaintiff's claim.