As of April 1, 2026, it has become possible to file European patent applications or enter the Euro-PCT phase in docx format.
According to the EPO’s press release, this new option applies to patent application documents, translations, amendments, annotated versions highlighting amendments, letters, and other submitted materials, including those originating from third parties.
The definition of the docx format accepted by the EPO is available here:
https://www.epo.org/en/legal/official-journal/2026/03/a23