According to the provisions of China's current law, the assignment of creditor's rights, also known as the assignment of contractual rights, is mainly reflected in the contract. This describes the transfer of all or part of the rights under the contract by a party to the contract to a third party outside the contract. However, if the creditor does not know or consent, how should the validity of such an assignment be determined? What issues do we need to pay attention to in the process of transferring creditor's rights? 
First, let's review a specific case. On February 6, 2022, Zhou borrowed 800,000 yuan from a company and agreed to return it within one year. Subsequently, Zhou lent the loan to Qiu, but Qiu did not return it. On May 6, 2023, the borrowing company transferred all of the debt to Liu. Liu then took Zhou to court. However, Zhou claimed that the transfer was invalid and refused to return the loan to Liu on the grounds that he had not been notified of the assignment of creditor's rights and without his consent. When the court heard the case, the focus of the dispute was on whether the assignment agreement was valid. Regarding Zhou's claim, the court held that although the assignment of creditor's rights had not been agreed to by him, Liu had already filed a lawsuit. According to the relevant provisions, the time when the complaint is served on the debtor shall be the time of notification, and the assignment of creditor's rights shall have legal effect on the debtor. This means that the effectiveness of the debtor's performance of the obligation to the assignee does not depend on the debtor's commitment. Mr. Liu held the original agreement on the transfer of creditor's rights from the borrowing company and the original IOU issued by Mr. Zhou, which was sufficient to prove the fact of the assignment of creditor's rights. Therefore, the court did not support Zhou's claim. So, what issues do we need to pay attention to when transferring creditor's rights? First of all, depending on the nature of the contract, some contracts are not transferable. For example, contracts concluded based on a relationship of trust between the two parties, such as partnership contracts, guarantee contracts, etc., may not be transferred without consent. Secondly, if there is a clause in the contract that it is not assigned, then the assignment of the claim cannot be carried out in this case. This embodies the principle of freedom of contract. Finally, some claims are not assignable under the law. In addition, the creditor does not need to obtain the approval or consent of the other party to transfer its rights, but the other party should be notified. Once such notice has been served on the other party, the transfer is complete. Such notification may be in writing or orally, but it is more appropriate to do so. This is because the written notice can be used as evidence for future dispute resolution. To sum up, although the assignment of creditor's rights is complex, there are rules to follow in practice. As long as we pay attention to the above key points and operate in strict accordance with the law, disputes and risks can be effectively avoided. The legal provisions on the assignment of creditor's rights:
1.If the creditor transfers its rights, it shall notify the debtor. Without notice, the assignment is not effective against the debtor. Notice of the assignment of rights by a creditor may not be revoked except with the consent of the assignee.
2.After the debtor receives the notice of assignment of creditor's rights, the debtor may assert against the assignor the defense against the assignee.
3.If the debtor transfers its obligations, the new debtor may assert the original debtor's defense against the creditor; If the original debtor has a creditor's right against the creditor, the new debtor may not claim set-off against the creditor.
4.If the creditor transfers all or part of the creditor's rights without notifying the guarantor, the transfer shall not be effective against the guarantor. If the guarantor and the creditor agree to prohibit the assignment of creditor's rights, and the creditor transfers the creditor's rights without the written consent of the guarantor, the guarantor no longer bears the guarantee liability to the transferee.
5.If the creditor and the third party reach an agreement to transfer all or part of the creditor's rights to the third party, the rights and obligations of the original creditor to the third party shall be terminated as of the effective date of the agreement.
If the creditor does not notify the debtor of the assignment of the creditor's rights, does the debtor know whether the assignment is valid after the lawsuit is filed? According to the laws of China, the creditor shall notify the debtor when transferring the creditor's rights, otherwise the transfer will not be effective against the debtor. If, after the creditor has assigned the claim, the debtor has not been notified and is aware of the assignment after the lawsuit has been filed, the assignment is considered invalid in law.
However, in some cases, if the creditor has fulfilled its obligation of reasonable notice at the time of the assignment, the assignment may still be considered valid even if the debtor has not been notified. This usually occurs when the debtor is unable to receive timely notice from the creditor for various reasons, or the debtor does not discover the assignment in time after the assignment of the creditor's rights has occurred.
Therefore, when judging whether the creditor's act of transferring the creditor's right is valid, it is necessary to make a judgment based on the specific circumstances. If the creditor has fulfilled a reasonable duty of notice at the time of the assignment of the claim, and there are no other illegal acts, then the assignment can be regarded as valid. If the creditor fails to fulfill the notification obligation or there are other illegal acts, then the transfer is deemed invalid under the law.