A contract signed by a wife rather than a husband is usually valid. Signing a contract is the act of signing a contract on behalf of others, which requires the authorization of an agent. The power of attorney shall specify the wife's name, agency matters, authority and time limit, and shall be signed or sealed by the husband.

legal ground

Article 17 1 of the Civil Code

If the actor has no power of agency, exceeds his power of agency or terminates his power of agency, he will still carry out the agency act, and it will have no effect on the principal without ratification by the principal. The counterpart may urge the principal to ratify it within 30 days from the date of receiving the notice. If the trustor fails to declare it, it shall be deemed as refusal to ratify it. Before the act committed by the actor is ratified, the bona fide counterpart has the right to revoke it. Revocation shall be made by notice. If the act committed by the actor is not ratified, the bona fide counterpart has the right to demand the actor to perform the debt or demand the actor to compensate for the damage he has suffered. However, the scope of compensation shall not exceed the benefits that the counterpart can obtain when the principal ratifies. If the counterpart knows or should know that the actor has no right to act as an agent, the counterpart and the actor shall bear the responsibility according to their respective faults.