Legal analysis: the interest of IOUs is more than four times that of banks, and the principal has legal effect. According to the Supreme People's Court's judicial interpretation, the interest of private lending that exceeds 4 times (including interest rate) of similar bank loans in the same period is not protected, but the loan principal and interest within 4 times are still protected.

Legal basis: Article 6 of "Several Opinions of the Supreme People's Court on People's Courts Handling Loan Cases" can be higher than the bank's interest rate, and local people's courts can specifically grasp it according to the actual situation in the region, but the maximum shall not exceed 4 times (including interest rate) of the bank's similar loan interest rate. Beyond this limit, the excess interest will not be protected.