according to the theory of civil law debt commitment, there are two main types of debt commitment: one is exempt debt commitment, which is usually called debt transfer, and the other is coexisting debt commitment, which is usually called debt joining. Article 84 of the Contract Law (Article 551 of the Civil Code) stipulates the exemption of debt commitment, but the Contract Law does not stipulate the content of coexisting debt commitment, and the Civil Code formally incorporates the coexisting debt commitment into the code, thus constructing a relatively complete debt commitment system.

Legal basis:

Article 552 of the Civil Code of the People's Republic of China mainly includes: First, the original creditor-debtor relationship exists effectively; Second, the debtor is not divorced from the debt relationship. After the third party joins the debt, the original debtor should still undertake the performance obligations within the scope of the original debt, and it is not exempted from its performance obligations because the third party joins the debt, that is, the third party only adds a new debtor on the basis of the original debtor, which has the function of guaranteeing the realization of creditor's rights in nature; Third, the creditors should be notified. Although the third party does not need the creditor's consent to join the debt, it should be notified to the creditors, or the third party directly expresses its willingness to join the debt to the creditors. If the creditors do not explicitly refuse it within a reasonable period of time, it will not be effective to the creditors. At the same time, the creditors, as obligees, can refuse the third party's debt participation. Fourth, the third party is jointly and severally liable with the debtor to the creditor within the scope of the debt it is willing to bear.