Is it legally binding to sign the IOU?

Legal analysis: IOUs have legal effect. As long as it is signed voluntarily by a person with full capacity for civil conduct, and the content of the loan is legal, the loan is valid. An iou is a certificate issued by the debtor to the creditor indicating that it still owes something or a certain amount, which is generally used to prove the relationship between creditor's rights and debts.

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

Article 667 A loan contract is a contract in which the borrower borrows money from the lender, repays the loan at maturity and pays interest.

Article 668 A loan contract shall be in written form, unless otherwise agreed between natural persons.

The contents of a loan contract generally include terms such as loan type, currency, purpose, amount, interest rate, term and repayment method.

Article 669 When concluding a loan contract, the borrower shall, at the request of the lender, provide the true information about the business activities and financial status related to the loan.