1. It is fraudulent to conclude a contract without using your real name. According to the provisions of the Civil Code, if one party uses fraudulent means to make the other party conclude a contract against its true meaning, the injured party has the right to request the people's court or an arbitration institution to change or cancel it.
2. If the signed pseudonym does not match the household registration, but belongs to other names used to express the actor's meaning in daily activities, if the signing behavior is the expression of the actor's true meaning and does not make the other party violate the true meaning, the signed contract shall be a valid contract agreed by both parties.
3. If the actor signs his name on the premise that it may infringe the interests of others, and the other party violates his true meaning without knowing it, the effectiveness of the actor's signature behavior is to be determined, and the contract can be revoked or changed.
Is it illegal to sign a contract under a pseudonym?
Whether it is illegal to use a pseudonym when signing a contract depends on the specific situation. If the pseudonym is used only for the purpose of protecting personal privacy, and the contractual obligations have actually been fulfilled, then the contract is still valid and not illegal. For the purpose of illegal possession, a fictional unit or a person signing a contract in the name of another person defrauds the other party of property in the process of signing and performing the contract, which is suspected of contract fraud in the criminal law. The minimum sentence is fixed-term imprisonment of not more than three years or criminal detention, and a fine is also or only imposed.
Legal basis:
Contract law of the people's Republic of China
Article 54 One party has the right to request the people's court or an arbitration institution to modify or cancel the following contracts: (1) Contracts concluded due to gross misunderstanding;
(2) obviously unfair at the time of conclusion of the contract. If one party leads the other party to conclude a contract against its true meaning by fraud, coercion or taking advantage of others' danger, the injured party has the right to request the people's court or arbitration institution to modify or cancel it. The people's court or arbitration institution shall not revoke the request of the parties.