Once the offer is presented, the offeree can decide whether to accept or reject the proposal. The offeree can communicate acceptance either verbally or in writing (including mail or email)*.
Acceptance can take many forms, including:
- Conditional Acceptance
- Acceptance by Action
- Option Agreement
In general, a counter-offer is considered a termination of the original offer, but some circumstances allow for conditional acceptance. For example, the Universal Commercial Code (UCC) acknowledges the validity of new conditions to an offer, as long as those conditions are made known to both parties and do not cause surprise or hardship.
Inaction is not considered acceptance for the purposes of a contract. This goes back to a legal tenant established in 19th Century Britain. In that contract case, a man offering to buy a horse declared that he would consider the horse purchased unless he heard otherwise from the seller. The court determined that assumption cannot create a contract. Acceptance must be explicit; merely taking action on one side (for example, shipping unsolicited materials) is not enough. Both sides must act, but if the actions are explicit and declarative, they will rise to the level of acceptance for the purposes of the contract.
*In most states, an offer is considered accepted once it has been placed in a mailbox. The mailbox rule applies even if the acceptance is never received by the offeror. The main rule of validity for an acceptance is that it must be a clear and direct statement that all terms and responsibilities in the contract are accepted.