Does it have legal effect to sign an IOU in white paper?

Legal analysis: As long as all parties are sincere and reach an agreement through consultation, and do not violate relevant mandatory laws and regulations, the white note is valid as long as it is written and signed. However, it is necessary to clearly write down the loan amount, agreed interest, repayment time and ID number of both parties.

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.