Legal analysis: Yes, the IOU is a form of loan contract. The IOU can only be declared established after both parties sign or seal it, otherwise it will not have legal effect.

Legal basis: "The People's Republic of China and the Civil Code"

Article 667: The loan contract means that the borrower borrows money from the lender and returns the loan and pays when due interest contract.

Article 668: A loan contract shall be in written form, unless otherwise agreed upon for a loan between natural persons. The content of a loan contract generally includes terms such as loan type, currency, purpose, amount, interest rate, term and repayment method.

Article 490: If the parties conclude a contract in the form of a contract, the contract shall be established when both parties sign, seal or fingerprint. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it. Laws and administrative regulations stipulate or the parties agree that a contract should be concluded in written form. If the parties do not use written form but one party has performed its main obligations and the other party accepts it, the contract is established.