Legal analysis: Legally speaking, IOUs can be handwritten or printed. However, considering that in practice, the printed IOUs are only signed by the borrower, and it is controversial that the borrower claims to sign on white paper and print it by others afterwards, it is best to write the IOUs by hand. The printed IOU shall at least have the following basic contents: the name information of the borrower and the borrower, the loan amount, the loan term, the interest, the liability for breach of contract, the borrower's signature and the date of signature.

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.