Filing colour drawings at the EPO: what applicants need to know

Background

As of 1 October 2025, the EPO accepts colour drawings in patent applications. The EPO does not charge any additional fees for filing colour drawings compared to black and white or grayscale.

Among major offices, so far only the South Korean IPO has adopted a similar general practice. However, the USPTO may allow for colour drawings to be filed in rare circumstances when necessary for accurate depiction of the invention. 

This development from the EPO may encourage other offices to revise their rules.

International strategy for filing in colour

Applicants should consider their international filing strategy carefully.

If filing exclusively at the EPO, there are no apparent disadvantages to using colour drawings. 

However, some jurisdictions might require black and white drawings. In such cases, claiming priority from an earlier filed application with colour drawings might affect the validity of a priority claim. 

PCT applications

A PCT application can be filed with colour drawings, but WIPO will automatically convert any colour drawings to black and white.  This automatic conversion could result in a loss of information or detail that could be problematic.  Therefore, although the, original colour drawings are retained and are can be viewed on PATENTSCOPE, there is a significant risk in filing colour drawings in a PCT application.

However, Euro-PCT applications can enter the European phase with colour if they were included in the initial PCT filing.

Colour photographs

Current practice at the EPO (24th version of the European Patent Guide, dated before the rule change) is to convert colour photographs to black and white for electronic files. No official guidance has been issued on accepting colour photographs specifically, though updated guidance may appear in the upcoming 25th edition of the European Patent Guide. The EPC has no express provisions for photographs generally, so it may be the case that colour photographs are acceptable by default following the colour drawings ruling.

Effect on priority

Standard priority rules apply. Adding colour drawings to later filings when the priority application contained only black-and-white drawings will be treated as added subject matter. To claim priority with colour drawings, the priority application must originate from a jurisdiction that permits colour drawings.

Key considerations

Colour drawings can enhance European filings, but global consistency remains critical. Applicants should plan ahead to avoid added subject matter issues and priority risks.

In summary, it is recommended that applicants:

• Confirm acceptance of colour drawings in all target jurisdictions ahead of filing.
• Prepare black and white drawings, if target jurisdictions do not allow colour.
• Avoid introducing colour later, as this could create added subject matter.

If you have any questions regarding this article, or would like further assistance, please contact your usual Swindell & Pearson attorney or Oliver McHugh, the author of this article.