The IOU can be sued for ten years, but if it has exceeded the limitation of action, if the other party raises a defense against the limitation of action and finds out that there is no reason for suspension, interruption or extension, the court will reject its claim.
 [Legal Basis]
 In Article 188 of the Civil Code, the limitation period of action for requesting the people's court to protect civil rights is three years. If the law provides otherwise, such provisions shall prevail.
 The limitation period of action shall be counted from the date when the obligee knows or should know that his rights have been damaged and the obligor. If the law provides otherwise, such provisions shall prevail.
 However, if it has been more than 20 years since the date of damage to rights, the people's court shall not protect them. Under special circumstances, the people's court may decide to extend them on the application of the obligee.