Print out the IOU and the debtor will sign it. As long as the signing party has the corresponding capacity for civil conduct, the behavior is the expression of its true meaning, and it does not violate the legal provisions or public order and good customs, the IOU is legal and valid.

Legal objectivity:

People's Republic of China (PRC) Civil Code

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.

People's Republic of China (PRC) Civil Code

Article 20

Minors under the age of eight are persons without capacity for civil conduct, and their legal representatives act as agents to carry out civil legal acts.