According to the law, a legally established contract takes effect from the time it is established. The Contract Law stipulates several situations of invalid contracts. Therefore, a housing lease contract is valid if its content is legal and there is no legal invalidity, and vice versa.
 Article 146 of the Civil Code: The civil legal act performed by the actor and the counterpart with false intention is invalid.
 The validity of a civil juristic act concealed by a false declaration of intention shall be dealt with in accordance with the provisions of relevant laws.
 Article 153 A civil juristic act that violates the mandatory provisions of laws and administrative regulations is invalid. However, the exception is that the mandatory provisions do not invalidate the civil juristic act.
 Civil juristic acts violating public order and good customs are invalid.
 Article 154 A civil juristic act that the perpetrator maliciously colludes with the counterpart and damages the lawful rights and interests of others is invalid.
 Article 155 An invalid or revoked civil juristic act is not legally binding from the beginning.
 Article 156 If part of a civil juristic act is invalid, which does not affect the validity of the other parts, the other parts remain valid.