Background and Objective: Any lawsuit brought during the proceedings of another case by the plaintiff, the defendant, a third party, or the main parties against a third party is referred to as an “incidental claim” (Da’va-ye Tāri). If this claim is related to or shares a common origin with the main claim, it must be filed in the same court where the main claim has been lodged. The possibility of raising incidental claims in both arbitration and judicial proceedings has been acknowledged by the legislator. The legislator has established specific conditions for filing such claims in arbitration and court proceedings. The purpose of this study is to comparatively examine these conditions in the two forums.

Method: This study follows a descriptive-analytical method.

Ethical Considerations: Throughout the writing of this article, textual originality, honesty, and academic integrity have been observed.

Findings: Incidental claims in both judicial and arbitral proceedings are subject to general and specific conditions, including the existence of a legal interest, legal capacity, standing (i.e., locus standi), a necessary connection or common origin with the main claim, submission within the prescribed time limit, and adherence to subject-matter jurisdiction.

Conclusion: The comparative analysis shows that although there are similarities in the conditions for filing incidental claims in court and arbitration, there are also significant and essential differences. These differences primarily stem from the consensual and contractual nature of arbitration.