The offer letter itself is a simple personal letter written by a prospective homebuyer to a seller and has no legal binding. The formal offer (which typically accompanies the offer letter) is a binding agreement that, if accepted and signed by the seller, becomes a legally binding contract to purchase the home. There are typically built-in contingencies that offer buyers a “way out” on an accepted offer, but you would need to consult with legal counsel for details on your specific offer.