Legal analysis: effective. Generally speaking, a legal and valid contract or agreement should meet the following requirements: first, both parties are true and voluntary; The two sides signed the IOUs, not out of fraud or coercion. Second, have the corresponding capacity for civil conduct; For example, if a creditor borrows money, he must have the right to dispose of it, while if a debtor borrows money from a creditor, he must have the civil capacity to borrow money as a creditor, but not a minor. Third, the content is not illegal. The purpose of IOUs should be legitimate. If the purpose of the IOU is for illegal reasons, the IOU is invalid. The IOUs between relatives must also have the above three elements to be effective. As long as both parties sign voluntarily, both creditors and debtors have corresponding capacity for civil conduct at the time of signing, and the loan is legal, then the IOU between relatives is valid.

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.