1. According to the laws of our country, the IOU is a written contract, which is established when both parties sign or seal it, while a legally established contract becomes effective upon its establishment.

2. Legal basis:

1) Contract Law Article 32 If the parties conclude a contract in the form of a contract, the contract shall be established when both parties sign or seal it.

2) Article 44 of the Contract Law: Validity of a Contract A legally established contract becomes effective upon its establishment.

Where laws and administrative regulations stipulate that examination and approval, registration and other procedures shall be handled, such provisions shall prevail.