Article 47

Notice from the European Patent Office dated 11 September 2026 concerning the update of the definition of “DOCX” for filing with the European Patent Office

1. Since 1 April 2026, documents can be filed with the EPO in DOCX format in both proceedings under the European Patent Convention (EPC) and proceedings related to European patents with unitary effect. Following feedback from users, the definition of “DOCX” for filing with the EPO has been updated to enable more widespread use of this new filing format.¹ Version 4 of the definition will enter into force on 1 October 2026, replacing version 3.²
2. The update does not affect the existing requirements for the DOCX format. It merely extends the types of DOCX documents accepted, with a view to ensuring that DOCX files prepared using the most commonly used software and operating systems are compliant with the definition. The revised definition incorporates the ISO/IEC 29500:2016 standard and introduces support for both strict and transitional Open XML conformance variants as well as Aptos as additional supported Unicode font.
3. The update does not affect the scope and the conditions for the filing of documents in DOCX format. These remain as set out in the President’s decisions dated 25 March 2026 concerning the electronic filing of documents³ and concerning the filing of documents during telephone consultations and during interviews and oral proceedings held by videoconference⁴ and as further explained in the notice from the European Patent Office dated 25 March 2026 concerning the filing of documents in DOCX format.⁵ Insofar, it does not require users to change their filing practice.