No. A seller has no legal duty to respond to an offer in any particular way. A verbal counteroffer could expedite negotiations for the sale of a property in many cases. Of course, once there is an agreement about the terms and conditions of the sale, the parties should promptly reduce the agreement to writing and sign the contract to make it a binding obligation.
A seller could respond to a buyer’s offer by using the Seller’s Invitation to Buyer to Submit New Offer (TAR 1926). This form would be particularly useful when the seller’s proposal contains several changes to the buyer’s offer. By using this form, the seller is free to consider other offers without having to be concerned about the withdrawal of a previous, written counteroffer.