There are several ways to confirm that IOUs are forged: 1. You can apply to the relevant institutions for technical appraisal to identify the handwriting, fingerprints and seals of the IOUs; 2. Comprehensive judgment based on other evidence, such as whether there is actual capital flow, or relevant settlement vouchers, witness testimony and other evidence. Legal basis: Article 76 of the Civil Procedure Law, the parties may apply to the people's court for an appraisal on the specialized issue of finding out the facts. If the parties apply for appraisal, the qualified appraisers shall be determined by both parties through consultation; If negotiation fails, it shall be designated by the people's court. If the parties concerned do not apply for identification, and the people's court considers it necessary to identify specialized issues, it shall entrust a qualified appraiser for identification.