Legal analysis: Handwritten IOUs have legal effect as long as the meaning is true and does not violate the law. The specific requirements are as follows: (1) Write the full names of both borrowers and borrowers clearly; The loan amount should be clearly written, including the amount expressed in words and figures; The term of the loan should be clearly written, including the start and end dates of the loan and a clear term of the loan.

Legal basis: According to Article 490 of the Civil Code of People's Republic of China (PRC)? If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it.

A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.

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.