In the absence of other contracts, the IOU itself is a simple contract, so we should pay attention to whether the constitutive elements of the IOU are complete, including (but not limited to): the amount owed, the repayment time, the borrower's personal signature and the establishment time of the IOU.

Main items of formal IOUs:

1. The borrower should write the full text of the loan and sign it, not print it;

2. The loan content is accurate and unambiguous;

3. It is required to write down the borrowing time, borrowing purpose (the purpose should be legal and cannot be used for illegal purposes such as gambling), interest agreement and repayment period;

4. Lenders should try not to pay in cash, especially for large loans, and should use bank remittance, and the other party's account name is the same as that of the borrower; If the other party's credit or repayment ability is poor, you can ask for a guarantee or guarantor.

5. If there are many things that need to be agreed by both parties, they can sign a loan contract, and make detailed agreements while writing the IOU.

As long as the reason and amount of arrears are clearly written, the debtor's signature has legal effect.

To sum up, the legal full names of the borrower and the lender should be clearly written on the IOU; The amount of the loan should be clearly written on the receipt, including the amount in words and figures; The term of the loan should be clearly written on the receipt, including the start and end date of the loan and the clear term of the loan; The specific repayment date should be clearly written on the IOU.

Legal basis:

Article 667 of the Civil Code of People's Republic of China (PRC)

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 provide true information on the business activities and financial status related to the loan as required by the lender.

Article 679

A loan contract between natural persons shall be established when the lender provides the loan.