It depends on the situation. If the developer does not have the qualification to sell commercial housing and does not refund the deposit, it is illegal. If the conditions for the sale of commercial housing are not met according to the law, the developer shall not sell the commercial housing nor charge any fees of the nature of the advance payment. Therefore, if the commercial housing does not meet the sales conditions, and the buyer has already paid the "deposit", the developer should unconditionally return the deposit to the buyer regardless of whether the two parties have agreed on the return of the "deposit".
 Legal basis: Article 22 of the Measures for the Administration of Commercial Housing Sales
 Provisions: If the conditions for the sale of commercial housing are not met, the developer shall not sell the commercial housing nor charge any fees of the nature of the reservation money.