R. 97(1) EPC (Art. 106(4) EPC 1973) states that the apportionment of costs of opposition proceedings cannot be the sole subject of an appeal. As a rule, therefore, an appeal relating to apportionment of costs must be regarded as inadmissible if the appeal relating to the revocation of a patent is rejected as inadmissible for lack of merit and there is no other admissible request. However, if the impugned decision did not take into account the withdrawal of the request for oral proceedings and is thus based on a substantial procedural violation, the part of the impugned decision relating to apportionment of costs must be set aside (see e.g. T 154/90, OJ 1993, 505).

In T 1237/05 the board found that the opponent, not being adversely affected by the patent's revocation, was not entitled to appeal solely against the apportionment of costs. The opponent's appeal, in view of Art. 106(4) EPC 1973, was inadmissible on that count alone. The mere fact that an appeal, in this case the proprietor's, was admissible did not in itself make the opponent's appeal admissible (the opponent in any case not being adversely affected by the first-instance decision on the merits) because it related only to cost apportionment. A distinction had to be drawn between appeal proceedings (initiated by at least one admissible appeal) and an appeal lodged by a party; the wording of Art. 106(4) EPC 1973 clearly referred to an appeal lodged by one of the parties to the proceedings, regardless of the existence of other appeals lodged by the other parties.

In T 753/92 respondent I was adversely affected by the decision under appeal only in so far as their request for apportionment of costs was rejected. If respondent I had lodged an appeal against this decision, the appeal, with the apportionment of costs as its sole subject, would have been inadmissible under Art. 106(4) EPC 1973. The fact that respondent I submitted the request for apportionment of costs merely as a party to the appeal proceedings as of right (Art. 107 EPC) could not render such a request admissible without contravening the principle of equal treatment.

In T 668/99 the board took the view that, since no appeal had been lodged against the opposition division's decision on costs, that decision had become final upon expiry of the time limit for filing a notice of appeal (see also T 161/17). It found that the decision on costs mentioned in the request had not been submitted with the appeal, nor was there any indication of an implicit challenge to that decision. The board held that, unlike general procedural requirements, which – as had been consistently held – had to be reviewed at all times, including in the appeal procedure, the issuance of a decision on costs by the EPO did not necessarily mean that a decision had also to be reviewed by the EPO. The review of a decision at a higher level of jurisdiction required an appeal by one of the parties.

In T 420/03 the question arose whether the "additional decision" concerning the apportionment of costs fell within the scope of appeal. While the notice of appeal remained completely silent as regards the decision on the apportionment of costs, the request for cancellation of this decision was contained in the statement setting out the grounds of appeal. In the case before it, the board found that the notice of appeal did not contain any explicit statement concerning the apportionment of costs, and there was no other statement in the notice of appeal which could be interpreted – at least indirectly – that this was also the subject of the appeal.