Whether a spouse’s signature is valid or not depends on the circumstances.

As long as the house belongs to the joint property of husband and wife, it needs to be signed by both parties or entrusted to one party to sign, and an entrustment contract needs to be issued. If it is personal property, it must be signed by the individual. Can. Signing a contract requires the signature of both parties. If the purchase and sale of a house is a mutual act between husband and wife, both parties must sign. However, if one spouse entrusts the other to sign on his behalf, the contract will be valid only if signed by one party. If the authorization for agency is in written form, the power of attorney shall state the name of the agent, matters of agency, authority and term, and shall be signed or sealed by the principal. The IOU signed by one spouse is valid if the other party has the authorization. Only with the authorization can the other party sign on behalf of the other party. Debts borne by both spouses with the same consent, such as mutual signatures or subsequent ratification by one spouse, are joint debts of the spouses, and both spouses are obliged to pay off the debts.

The three conditions for a valid contract are as follows:

1. The actor has the corresponding capacity for civil conduct;

2. The intention is true;

3. Do not violate the mandatory provisions of laws and administrative regulations, and do not violate public order and good customs.

To sum up, the signature of one spouse when buying and selling a house is not necessarily valid. As long as the house is the joint property of the couple, both parties must sign together or entrust one party to sign. At the same time, it is necessary to Issue an entrustment contract. If it is personal property, it must be signed by the individual. The parties may entrust an agent to perform civil legal acts in accordance with the law. The principal shall bear the consequences and bear the responsibility for the agent's acts within the scope of authorization. Therefore, the contract does not need to be signed by the person but is still valid if it is signed by an agent. The legal consequences of a contract signed by an agent shall be borne by the agent. In other words, a contract signed by a couple is valid if they are authorized. .

Legal basis:

Article 161 of the "People's Republic of China and Civil Code"

Civil subjects may enforce civil laws through agents Behavior.

According to legal provisions, agreement between the parties or the nature of the civil legal act, civil legal acts that should be carried out by the person himself shall not be represented by an agent.