The law does not stipulate this. When buying a house, both parties agree to come, and they can engrave their official seals privately or press their handprints.

1. According to Article 32 of the Contract Law, if the parties conclude a contract in the form of a contract, the contract is established when both parties sign or seal it.

2. When the parties sign a contract, the unit must seal it, and the personal signature or fingerprint of the individual citizen shall prevail. Because in our country, except for the official seal of the unit and the private seal of the legal person, the private seal of citizens is basically not filed, which is arbitrary, neither standardized nor easy to forge.

3. Article 5 of Interpretation II of the Contract Law stipulates that "if the parties conclude a contract in the form of a contract, they shall sign or seal it. If the parties press their fingerprints on the contract, the people's court shall determine that it has the same legal effect as the signature or seal. "

4. Therefore, there is no need to sign a contract for purchasing commercial housing and a loan contract for provident fund and commercial loans, only the borrower himself needs to sign and affix the handprint of his right index finger (usually the index finger and thumb, depending on the requirements of the collection agency).