As long as the Buyer and the Seller sign the relocation house sales contract on the basis of equality and voluntariness through negotiation, which is the true intention of both parties, and the content of the contract does not violate the mandatory provisions of the law or the social and public interests, the house sales contract shall be legal and valid. According to the provisions of Article 52 of the Contract Law, a contract is invalid under any of the following circumstances: one party entered into a contract by means of fraud or coercion, thereby harming the national interests; Malicious collusion harms the interests of the state, the collective or a third party; Cover up illegal purpose in legal form; Damage to social and public interests; Violation of mandatory provisions of laws and administrative regulations. According to Article 38 of the Real Estate Management Law, the house property that has not been registered and received the ownership certificate according to law shall not be transferred. To sum up, because the Real Estate Management Law only states that transfer is not allowed, the real legislative intention of this article is not to prohibit transfer, but to facilitate administrative management, which is not a ban on contract effectiveness. Although the resettlers have not obtained the property ownership certificate, they enjoy quasi ownership of the house and have the right to dispose of the house they have placed. Before obtaining the real estate ownership certificate, he has the right to transfer the creditor's rights in the sales contract. Extended reading of relevant knowledge: What are the risks of buying a house for relocation? The house for relocation listed in the second-hand market accounts for about 10% of the whole second-hand market. In general, there are two situations for these returned houses: one is that the owner already holds the property certificate, and the other is that the owner only holds the return agreement. （1） The owner has obtained the Property Ownership Certificate of the commodity community. These returned houses can be used for second-hand sales or leasing transactions, because in the process of second-hand transactions, the Property Ownership Certificate is recognized and supervised by the Housing Authority. Therefore, the returned houses with the Property Ownership Certificate can be transferred and renamed in the exchange normally, which is very secure for buyers, and there is no need to worry about other things. （2） If the owner only has the developer's relocation agreement, and the owner of these houses only has the developer's relocation agreement, notarization transfer and name change cannot be done in the real estate exchange when doing second-hand transactions. Because the relocation agreement is only a private commercial agreement between the owner and the developer, this agreement has not been recognized by the Housing Authority. Therefore, when both parties conduct transactions, they can only do notarial transactions in the notary office, and can only do real transfer transactions after the House Property Certificate is issued.