Legal analysis: it is effective. As evidence, the IOU has no ID number, but it is equally valid as long as both parties sign and confirm and indicate the IOU content. A legally established contract is legally binding on the parties. A contract is formed by the unanimous expression of will by both parties. As long as it does not violate the freedom of contract and the law, the contract generally takes effect immediately.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 143 A civil juristic act that meets the following conditions is valid:

(1) The actor has corresponding capacity for civil conduct;

(2) the meaning is true;

(three) does not violate the mandatory provisions of laws and administrative regulations, and does not violate public order and good customs.

Article 135 A civil juristic act may be in written form, oral form or other forms; Where laws and administrative regulations stipulate or the parties agree to adopt a specific form, it shall adopt a specific form.