Legal analysis: According to the provisions of the Patent Law, if the applicant submits the application documents directly to the reception office or agency of the Patent Office, the filing date is determined as the filing date after on-the-spot examination. If the application documents mailed by the applicant meet the acceptance conditions, the mailing date shall be the application date. After the application date is determined, it cannot be changed at will. "
Legal basis: Article 28 of the Patent Law of People's Republic of China (PRC). The date when the patent administrative department of the State Council receives the patent application documents is the filing date. If the application documents are mailed, the postmark date of mailing shall be the application date.