A paper copy of the previous application for which priority is claimed (priority document) must be filed before the end of the sixteenth month after the date of priority. Priority documents may not be filed in electronic form unless they have been digitally signed by the issuing authority and the signature is accepted by the EPO (see the Decision of the President of the EPO dated 10 November 2015, OJ EPO 2015, A91, and the Notice from the EPO dated 15 September 2004, OJ EPO 2004, 562). Nor may they be filed by fax (see the Decision of the President of the EPO dated 12 July 2007, Special edition No. 3, OJ EPO 2007, A.3). Where multiple priorities are claimed, the above-mentioned time limit runs from the earliest date of priority.
The copy must be certified as an exact copy of the previous application by the authority which received the previous application and must also be certified by that authority as to its date of filing. This certification of the date may take the form of a separate certificate issued by that authority stating the date of filing of the previous application (Rule 53(1), second sentence) or may be an integral part of the priority document itself. The certification of the authenticity of the copy may also be a separate document or an integral part of the priority document.
It is also possible to file a copy of the previous application (priority document) on physical media other than paper, e.g. CD-R, provided that:
The certificate(s) may be filed separately in paper form. The submitted medium must be readable and free of computer viruses and other forms of malicious logic.
then the EPO will include free of charge a copy of the previous application in the file of the European patent application. No request is necessary to this end. However, as regards Chinese patent or utility model applications, this applies only if these were filed on or after 3 September 2012. Moreover, if the language of the previous application was not one of the official languages of the EPO, it may still be necessary to file the translation or declaration under Rule 53(3) (see A‑III, 6.8).
Where the applicant has already supplied a copy of the priority in the context of a request to base late-filed parts of the description or drawings on the claimed priority under Rule 56 (see A‑II, 5.4(v)), the applicant does not need to file it again. However, if the copy already provided was not certified as to its content and/or filing date, the applicant will need to provide the missing certification within the above time limit.
If the applicant fails to provide a certified copy of the priority document within the above-mentioned period (Rule 53(1)), the EPO will invite him to provide it within a two-month period under Rule 59. This period can be extended under Rule 132(2) (see E‑VIII, 2.3.5, for Euro-PCT applications), but further processing is ruled out by Rule 135(2). If the applicant fails to provide it within this period, the priority right in question is lost (Art. 90(5)).