Comparative Study on Optional Fullfillment of Obligation

There are several challenges in optional fulfillment of obligation such az the elements of optional filfillment of obligation in comparison with similar titles, the types of optional fulfillment of obligation and reviewing that in gradable and nondegradable commitments. This article is to clarify the aspects  of optional fulfillment of obligation by comparative study on the legal systems of Iran and England and The result is that the voluntary execution of the commitment is that the promisor undertakes to carry out his obligation, whether to act or to leave, to deliver the goods to the will, without requiring a committed obligation through legal authorities. This implementation has elements that include knowledge of the act, independence in commitment and fulfilling the obligation in accordance with the contract. The titles used in English law in this area are capable of conforming to Iranian law.