Legal analysis: The IOUs played by WeChat have the same legal effect. As long as the IOUs are standardized and complete, they are protected by law. Pay attention to the following items when writing IOUs: 1. The date of arrears-it must be clearly written, preferably accurate to days, and the repayment date can be agreed in the IOU. If the repayment date is not agreed, the creditor may claim to return it at any time. If the repayment date is agreed, it can only be required when the repayment date expires. 2. The amount owed should be capitalized in Arabic numerals and Chinese at the same time, and the currency should be clearly written. 3. If the debtor is married, it is better to obtain the signature of the spouse, which is more secure for the creditor, and avoids that one party refuses to undertake the repayment obligation on the grounds of ignorance or court enforcement, and one party transfers the property to the spouse, resulting in inability to repay. 4. At the same time, collect the copy of ID card and marriage certificate signed by the debtor.

Legal basis: Article 16 of the Provisions of the Supreme People's Court on Several Issues Concerning the Application of Laws in the Trial of Private Lending Cases, the plaintiff filed a private lending lawsuit only on the basis of the transfer vouchers of financial institutions, and the defendant argued that the transfer was to repay the previous loans or other debts of both parties, and the defendant should prove his claim with evidence. After the defendant provides corresponding evidence to prove his claim, the plaintiff should still bear the burden of proof for the establishment of the loan relationship.