Is it illegal for buyers to keep the deposit?

Illegal. In the purchase contract, the property delivery deposit is a form for the buyer to pay the deposit, and its purpose is to ensure the performance of the contract. If the buyer fails to return the property delivery deposit as agreed, the performance of the contract will be affected. Therefore, it is illegal for the buyer not to return the property delivery deposit, and he should be liable for breach of contract, and the buyer will be liable for compensation if he does not return the property delivery deposit. Property refers to all kinds of houses and their supporting equipment, facilities and venues that have been built and put into use.