If both parties decide to sign the contract in writing, the contract will take effect immediately as long as both parties sign or seal it; When both parties decide to sign the contract in writing, the contract will come into effect as long as one party fulfills its main obligations and the other party accepts it. When the contract is signed, the official seal of the unit and the signature of the legal person have the same effect. However, if it is agreed at the time of signing the contract that the contract will take effect after being signed and sealed by both parties, in this case, if the contract is only sealed and not signed, the contract is not established and has no legal effect. Therefore, under normal circumstances, the contract is still valid unless the legal person signs the official seal.

legal ground

Article 490 of the Civil Code of People's Republic of China (PRC): If the parties conclude a contract in the form of a contract, the contract is concluded when the parties sign, seal or fingerprint it. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.