Legal analysis: 1. Only the borrower's signature is not allowed, and only personal loans have no legal effect. The basic contents of IOUs include: creditor's name, loan amount (local and foreign currency), interest calculation, repayment time, liquidated damages (deferred repayment), dispute resolution method, debtor's name, loan date and other elements.

2. If only the name of the creditor, the amount of the loan, the name of the debtor and the date of the loan (although it was added later), it meets the main requirements of the loan, so it has legal effect. Once a dispute arises, it can be used as evidence to claim creditor's rights to the people's court, and the people's court will accept it.

3. An IOU is a written document indicating the relationship between creditor's rights and debts, which is generally written and signed by the debtor, indicating that the debtor has owed the creditor the amount indicated on the IOU. An iou refers to a bill written to the other party when borrowing personal or public cash or goods, that is, an iou. After the money and goods were returned, the IOUs were revoked or torn up. This is a document. Usually used in daily life and business management.

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.