Can a seller back out of a firm offer in Ontario?

Once a seller has signed and accepted an offer and all conditions have been waived or fulfilled, the deal is firm and the seller is legally bound to complete it. Backing out without a valid legal reason constitutes a breach of contract.

The buyer's available remedies in Ontario include: keeping any deposit the seller may have provided (though most deposits come from buyers), suing for damages caused by the breach (such as costs of temporary housing and the difference if they buy a similar property at a higher price), or seeking specific performance — a court order requiring the seller to transfer the property. Courts have sometimes ordered specific performance for real estate because each property is considered unique.

The only circumstances where a seller might have a legal basis to exit the deal are if the contract itself was voidable (e.g., signed under duress or based on misrepresentation by the buyer) or if a condition favourable to the seller was properly invoked. Sellers who are considering walking away from a firm deal should speak with a real estate lawyer immediately before taking any action.