Legal analysis: if the official seal is not stamped on the words, it will be considered valid. If you write the words on the official seal later, there will be a difference. As for whether it is effective or not, it depends on whether the other party approves it. The contract requires both parties to express their agreement and then sign or seal for confirmation. If there is a seal first, then there is a text content, it cannot be considered that the meaning is consistent. Of course, if the other party approves it, it is considered effective.

Legal basis: Article 490 of the Civil Code of People's Republic of China (PRC). If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. 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.