Debit notes and IOUs signed by means of deception, threat, intimidation, deception, etc. are not protected by law. If we write down the IOU after being cheated, first of all, we should think about the alarm. Don't worry about anything. Alarm is the first thing to do. It is very important to look for witnesses and evidence, and write the IOU only when you prove that you have been cheated. You must recall the specific process and find witnesses and evidence. Tell the police the whole story truthfully, so as to help you better.
 Under any of the following circumstances, the contract or part of the contract terms may be deemed invalid:
 1. A contract concluded by one party through fraud or coercion that is detrimental to the interests of the State;
 2. A contract with malicious collusion that damages the interests of the state, the collective or a third party;
 3. A contract whose legal form conceals the illegal purpose;
 4. Contracts that damage the public interest;
 5. Contracts that violate the mandatory provisions of laws and administrative regulations;
 6. The contract terms exempting the other party from liability for personal injury or property loss caused by intentional or gross negligence;
 7. The provision that one party provides standard terms to exempt from liability, increase the liability of the other party, and exclude the main rights of the other party is invalid;
 8. The contract is invalid due to cancellation.
 How can the IOU be legally effective? 1. The full legal names of the borrower and lender shall be clearly written;
 2. The loan amount should be clearly written, and both Arabic numerals and Chinese words should be used, such as "RMB 100000 (one hundred thousand yuan)", to prevent tampering by the holder of the IOU;
 3. The loan term should be clearly written, including the beginning and ending date of the loan and the definite loan term, preferably accurate to date;
 4. The specific date of repayment shall be clearly written, but it is not necessary;
 5. The loan interest shall be clearly written, including the annual or monthly interest rate, and the total amount of the loan interest finally payable (including the amount in words and figures);
 6. The time and payment method of principal and interest repayment shall be clearly stated;
 7. The borrower shall have his own signature, seal, or handwritten signature;
 8. If the amount is large, a third party can be invited to witness and sign. Have you understood the legal content of the above IOU?
 Article 148 of the Civil Code of the People's Republic of China, if one party fraudulently causes the other party to commit a civil legal act against its true intention, the fraudster has the right to request the people's court or an arbitration institution to revoke it.
 Article 149 of the Civil Code of the People's Republic of China, if a third person commits a fraudulent act and causes one party to commit a civil legal act against its true intention, and the other party knows or should know about the fraudulent act, the fraudster has the right to request the people's court or arbitration institution to revoke it.
 Article 150 of the Civil Code of the People's Republic of China, if a party or a third person coerces the other party to perform a civil legal act against its true intention, the coerced party has the right to request the people's court or an arbitration institution to revoke it.