From: Judiciary answers to 14 Difficult Questions about Foreign-related Commercial Trials By Ningbo Intermediate People's Court, Zhejiang Province, PRC

Answer: Strictly speaking, the proforma invoice is only a document issued unilaterally and has no final binding force on both parties. However, if the proforma invoice is signed by the importer and sent back to the exporter by fax, mail or electronic document, which has the conditions for the establishment of the contract and does not have the conditions to prevent the validity of the proforma invoice, the proforma invoice becomes a document jointly signed by both parties, which has the nature of a contract. The content stated on it can be regarded as the agreed content of both parties, has the validity of the contract and is binding on both parties. If the importer does not sign back, but accepts it by its behavior, including continuing to carry out the transaction between both parties based on the proforma invoice, then the importer's behavior can be considered as an "implied commitment", which is an effective commitment, and the court can also consider that the proforma invoice has the contractual effect.