How to determine the date of patent application

Article 28 of the Patent Law of People's Republic of China (PRC) stipulates that the date when the patent administrative department of the State Council receives the patent application documents is the filing date. 1. If the applicant submits the documents to the Patent Office in person, the date when the Patent Office receives the documents is the filing date; 2. If the application documents are mailed, the postmark date of mailing shall be the application date; 3. If the postmark is illegible or illegible, the Patent Office will inform the applicant, and if the applicant can submit evidence of the exact date when the application documents were sent in the post office, the date of sending the documents will be the application date; 4. Where the applicant can't provide relevant supporting documents, the date of receipt of the application documents by the patent administrative department of the State Council shall be the filing date.