According to Art. 80, a European application is accorded as its date of filing the date on which it satisfies the requirements of Rule 40, or, if filed under the PCT, the date on which it satisfies Art. 11 PCT. This date remains unchanged except in the special circumstances of late-filed drawings or parts of the description provided for in Rule 56 EPC and Art. 14(2) PCT. and late-filed correct application documents or parts filed under Rule 56a.
The date of filing may be the only effective date of the application. It will be of importance for fixing the expiry of certain time limits (e.g. the date by which the designation of the inventor must be filed under Rule 60), for determining the state of the art relevant to the novelty or obviousness of the subject-matter of the application, and for determining, in accordance with Art. 60(2), which of two or more European applications from separate persons for the same invention is to proceed to grant.