| ||With respect to the time within which an offer must be accepted, this Article, which corresponds to the second part of paragraph (2) of Article 18 CISG, distinguishes between written and oral offers.
As concerns written offers, all depends upon whether or not the offer indicated a specific time for acceptance: if it did, the offer must be accepted within that time, while in all other cases the indication of assent must reach the offeror “within a reasonable time having regard to the circumstances, including the rapidity of the means of communication employed by the offeror”.
1. A sends B an offer on Monday indicating that if B intends to accept, it must do so by Friday at the latest. B’s acceptance reaches A on the Monday of the following week. A may reject B’s acceptance as being too late.
2. A sends B an offer on Monday morning by e-mail, urging B to reply “as soon as possible”. Although on previous occasions A and B had already communicated by e-mail, B accepts A’s offer by letter which reaches A on Thursday. B’s acceptance is too late since under the circumstances an acceptance by a letter which reaches A three days after its e-mail was not made “as soon as possible”.
Oral offers must be accepted immediately unless the circumstances indicate otherwise. An offer is to be considered oral not only when made in the presence of the offeree, but whenever the offeree can respond immediately. This is the case of an offer made over the phone or communicated electronically in real time.
It is important to note that the rules laid down in this Article also apply to situations where, in accordance with Article 2.1.6(3), the offeree may indicate assent by performing an act without notice to the offeror: in these cases it is the act of performance which has to be accomplished within the respective periods of time.
For the determination of the precise starting point of the period of time fixed by the offeror, see Article 2.1.8; as to the calculation of holidays falling within that period of time, see Article 1.12; as to cases of late acceptance and of delay in transmission, see Article 2.1.9.