Under R. 88(1) EPC (former R. 63(1) EPC 1973), the apportionment of costs is dealt with in the decision on the opposition. Only those expenses necessary to assure proper protection of the rights involved may be taken into consideration. This rule is frequently applied in the case law of the boards of appeal (T 167/84, OJ 1987, 369; T 117/86, OJ 1989, 401; T 416/87, OJ 1990, 415; T 323/89, OJ 1992, 169). On the costs of interpreting at oral proceedings, see Chapter III.C.5.2.
The costs include the remuneration of the parties' representatives. In T 854/09 the board stated that the costs concerned were those reasonably incurred by the opponent. In this case, where an adjournment of oral proceedings was necessary, this included the expense of a single representative preparing for and attending the second proceedings, including travel and accommodation. Under R. 88(2), last sentence, EPC, costs may be fixed once they have been established as credible. Therefore, the board in T 475/07 exceptionally took the view that a detailed cost calculation was superfluous. The board worked on the assumption that the representative could calculate on the basis of one day for preparing the additional oral proceedings and one day for attending them. The cost estimate of EUR 2 300 thus seemed credible.
In T 930/92 (OJ 1996, 191) the board held that, when fixing the amount of costs to be paid to a party, in addition to the remuneration of the professional representative of that party, the expenses incurred by an employee of that party in order to instruct the professional representative before and during oral proceedings could be taken into consideration under R. 63(1) EPC 1973, if such instruction was necessary to assure proper protection of the rights involved. In T 326/87 (OJ 1992, 522), all the costs incurred as a result of the remittal to the department of first instance were deemed to be apportionable.