Set-off in English Legal System with an Approach to Iranian law

Set-off between two mutal debts- that adopted in civil law system, and after the long ups and downs became as a substantive matter, accepted only as a procedural principle in English law too late between two debts caused by contract that contain a sum of money to prevent circuity of claims and it is a counter claim about a liquidated or sometimes unliqiudated sum of money which it time comes to execute and as a principle it only leads to stay of execution of plaintiff's claim. However, the existence of three legal sources of common law, equity and statute in mentioned legal system, led to formation of three distinct types of set-off that each of them is aplicable in it's own certain jurisdiction. These three types of Set-off which has not equivalents in civil law system and are recognized according to forms of relationship between two debts, can be nominated as integrated set-off, independet set-off and connected set-off. In Iranian law, although set-off causes to discharging of two debtors about a liquidated amount of mutal debts that it cames to execute, and extinguishes two debts, the existence of lien and nesessity of invoking in litigation, it bring closer the existent solution in Iranian law to solutions of English law. In this study it will been studied the approach of two mentioned legal systems about the basics of set-off, techniques and it,s differrent usages.