A copy of the previous application from which priority is claimed (priority document) must be filed before the end of the sixteenth month after the date of priority. Priority documents may be filed in paper form or electronically using OLF or CMS, provided the latter are in an accepted document format, have been digitally signed by the issuing authority and the signature is accepted by the EPO. Such electronic priority documents are currently being issued by the patent offices of the USA, Brazil, Portugal, Italy, Austria and Poland (in respect of the latter, for applications filed as of 14 October 2020), with further offices expected to follow. Web-Form Filing must not be used for the electronic filing of priority documents (see the Decision of the President of the EPO dated 15 November 2018, OJ EPO 2018, A93, and the Notice from the EPO dated 15 November 2018, OJ EPO 2018, A94). A priority document may not be filed by fax (see the Decision of the President of the EPO dated 20 February 2019, OJ EPO 2019, A18). Where multiple priorities are claimed, the above-mentioned time limit runs from the earliest date of priority.[Rule 53(1); Art. 88(2); Art. 90(4); ]

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.

At the request of the applicant, the EPO will include free of charge in the file of a European patent application a copy of the previous application from which priority is claimed retrieved via the WIPO Digital Access Service (DAS). DAS supports the automatic electronic exchange of priority documents within participating patent offices. Applicants may request the office of first filing (OFF) to make certified copies of previously filed patent applications available to the DAS system and then request offices of second filing (OSF) to retrieve the copies via DAS by indicating the DAS access code(s) corresponding to the previous application(s) (see the Decision of the President of the EPO dated 31 March 2020, OJ EPO 2020, A57, and the Notice from the EPO dated 22 February 2019, OJ EPO 2019, A27).[Rule 53(2); ]

If a priority document cannot be retrieved via DAS or if the applicant has not requested retrieval via DAS, the EPO will include free of charge a copy of the previous application in the file of the European patent application

if the previous application is:

No request is necessary to this end. In respect of Japanese patent or utility model applications (item (iv) above), this applies to European patent applications filed before 1 July 2020 and Euro-PCT applications entering the European phase before that date, and for which the required priority document can be included in the file of the application by 31 December 2021 (see the Notice from the EPO dated 31 March 2020, OJ EPO 2020, A58). 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 document 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 applicants fail to provide a certified copy of the priority document within the above-mentioned period (Rule 53(1)), the EPO will invite them to provide it within a two-month period under Rule 59. This period can be extended under Rule 132(2) (see E‑IX, 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)).[Art. 90(4); Art. 90(5); Rule 59; ]