A response that changes, adds to, or qualifies the material terms of the offer is not an acceptance. Acceptance, on the other hand, is the other party's expression of assent to the terms of an offer.(1) A definite and seasonable expression of acceptance or a written confirmation which is sent within a reasonable time operates as an acceptance. Offer and Acceptance In Contract Law. The foundation of any contract, verbal or written, is a valid offer and acceptance. An offer is a clear intention to enter into a legally binding agreement. It marks the first step in creating that agreement. Offer and acceptance. To create a contract, one party must make an offer that the other party accepts. 440.2206 Offer and acceptance in formation of contract. Sec. 2206.