European applications can be filed in any language. If filed in a language other than an official language of the EPO, a translation must be furnished. Consequently, the languages which can be used for filing European applications fall into three categories:
Furthermore, documents which have to be filed within a time limit may also be filed in an "admissible non-EPO language" if the applicant has his residence or principal place of business within the territory of a Contracting State having this as an official language or if the applicant is a national of such a Contracting State. See A-VII, 1.1 and A-VII, 1.2.
Subject to certain conditions, where an admissible non-EPO language is used, a reduction in fees (20%) is allowed. It serves to compensate the parties for the disadvantages that result from the fact that not all official languages of the Contracting States are official languages of the EPO. The conditions to be fulfilled for the grant of a reduction in fees vary for each procedural step for which a reduction is claimed (see G 6/91).
The reduction is only allowed if the translation into an EPO official language is filed in due time, that is to say at the earliest at the same time as when the European patent application or the document subject to a time limit is filed in the admissible non-EPO language (see G 6/91).